explored area of map disappears when expanding the map.

forgot to mention that if you expand the map outside of the place you create it then it gets "recreated" for the area where you expand it. 

Having to re-explore the area of a map after zooming it is intended behavior; see MCPE-16948.

I'm not sure what your comment is intended to say. Would a screenshot of the map make it clearer? It sounds as if you're saying that the part of the higher-level map that should corresponds to the unzoomed map, no longer does, but that seems very unlikely. Please provide a screenshot if you can and that would explain what you mean, or if you can't, perhaps you could describe using the specific coordinates.

i'm guessing you mean the comment part? so if i go to a new location and create a map in lets say section 2. if i then go back to section 1 and expand it then it erases everything explored (apparently its intentional for a map to be erased when expanded) but as i move around in section 1 the map is revealed so essentially where the map is expanded is where the map gets assigned to. so a map created in section 2 then expanded in section 1 becomes a map of section 1. 

From the terms "section 1" and "section 2" I can't deduce how those areas are related in space. Can you provide actual coordinates? (You can turn on coordinates in the world settings.)

A zoomed map should include the area of the unzoomed map as 1/4 of its content (once explored), so if section 1 and section 2 share an edge or a corner, it's likely that they would both appear on the zoomed map, in which case this is how it's intended to work. (Incidentally, if you had lower level maps of section 1 and section 2 and zoomed both of them, the zoomed maps would also have identical coverage areas.) It's not easy to predict which quarter of the zoomed map would contain the unzoomed map image, so I'd suggest you might need to explore the entire zoomed map area before you conclude that it's not mapping the right area.

Some additional info that might help in this case:
The way maps and zoomed maps related is that it's as if you took a level 0 map of the entire world and divided it into 128-block squares. Then you draw a box around the 4 center ones to make its level 1 map, and you tile the rest of the world map with 256-block squares. Then you do it again and tile the map with 512-block squares for level 2, and so on. So each level 0 map fits into one corner of a particular level 1 map, which fits into one corner (probably a different corner) of a particular level 2 map, etc. A lot of times people imagine that maps are centered around their position when they create them or something like that, but it's a misunderstanding. The map boundaries and correspondence between zoom levels are all predetermined before you start mapping. All creating a new map does is decide which of the level-0 maps it will show, namely the one you happen to be standing in.

meaning you create a map then expand it to 4/4 that first map is what i meant as section one. I have 24 maps fully expanded to 4/4 hung on a wall so i'm aware of how maps works. when i go to a new area and create a map then go to another area and expand it then it reverts to the area where it was expanded. i carry paper with me to expand the map where its created to avoid this glitch. 

if its not happening for you it may be just a glitch in my world. i have a work around for it so i'm not that worried about it. ty, you can close it out as resolved. 

@Auldrick based on what I'm seeing  the map origin changes when the map is expanded.

Essentially, every (I think) 6 chunks is a new map chunk, any maps created in a specific map chunk will share the same origin.

Once the user expands a map, if they are within a different map chunk, the origin of the expanded map changes.

For some visual...

Let's say the X represents the map chunk the map origin is located in, O represents a generic chunk, and Q represents the chunk the player is located in

OOOOO

OOQOO

OOXOO

OOOOO

as you cannsee, the player is one chunk north of where theap's origin is. Now if the player expands their map...

OOOOO

OOXOO

OOOOO

OOOOO

The map's origin shifted to where the player was located, rather than remaining where it originally was

Hope this helps

@unknown: Actually, a zoomed map's origin is the same as the original map only 25% of the time, and this is an unavoidable requirement in order to have walls maps with no overlaps nor gaps in them. The reasoning isn't intuitive, but it's supported by a solid mathematical proof.

The fact is that there's a fixed correspondence between maps of the same area at different zoom levels. What I mean by that is that each level 0 map "belongs to" a specific level 1 map, and its image can only appear (in scaled reproduction) in one specific corner of that level 1 map. I know it seems as if you could get it in a different corner by moving to a different level 0 area, but if you actually could do that, you'd be able to make different level 1 maps that contain the same area in different positions, and when you tried to hang them on a map wall you'd either have that area duplicated (because each map is in a different item frame) or you'd have to overlap them somehow (which you can't do with item frames). A level 1 map reproduces the scaled images of four level 0 maps, one in each of its corners. Since the map origin is in the upper left corner, only one of the four maps (25%) can have the same origin at both level 0 and level 1.

Obviously, this same analysis applies all the way up the zoom levels, so a level 1 map "belongs to" a specific level 2 map and its image can only appear in one specific corner of that level 2 map, and so on and so forth. The result is that fixed correspondence I'm talking about: For every point in the world, all the maps at different zoom levels that contain that point are positionally fixed in relationship to one another. Without this fixed correspondence, walls maps would be impossible, or at least extremely frustrating to build.

To respond to your diagram, the map origin did not "shift to where the player was located"; that was just a coincidence. Instead, the X in the first chart happened (25% chance) to correspond, per fixed correspondence, to the lower left corner of the zoomed map that it "belongs to". Think of a square drawn around the Q, the X, and the two Os to their right. That square represents the area covered by the zoomed map. If you zoomed any of the four lower level maps, it would have given you the same zoomed map; that's what the fixed correspondence does. You just happened to put the Q in the position of the map that, by coincidence, was in the upper left corner of the zoomed map. If you had instead swapped the Q and X in the chart, and then zoomed the map from X while standing at Q, it would have given you the same zoomed map and this time the origin would have been unchanged.

I have spent literally hundreds of hours studying how maps work and I could explain it more fully to you, but unfortunately the bug tracker isn't an appropriate place for it. (I've already written more than was necessary for bug tracking purposes, and we don't like to encourage people to treat this site like a help forum, because that creates a lot of clutter that interferes with bug tracking.) I occasionally appear on the Minecraft and Minecraft Wiki Discords; feel free to DM me there for more information if you like. I use the name Auldrick everywhere.

Cleaning up old tickets: This ticket has not been updated recently (~7 months+) so is being closed as Cannot Reproduce. If you feel this is still a valid issue and is affecting the most recent versions, then please comment, or create a new ticket following the Issue Guidelines.

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Re-resolving as a duplicate of MCPE-16948.