Zooming out a map loses all its data

I am having the same issue. I create a map and it works fine until I add the 8 sheets of paper to it. Once the 8 sheets are added the map becomes blank. I am playing Minecraft PE v0.16.2

Okay, it seems there are two things going on here:

1. The original issue described seems to be a "works as intended". Explored data, (as I understand how maps are intended) ALWAYS disappears when resized. If resized within the map location, there should be a small area explored. It seems the original user's anvil was off the edge of the later maps in screenshot 1. The "go to unexplored area" and "return to anvil/crafting table" were giveaways. That said, I think it would be AWESOME if maps retained data upon resizing. It would save much time re-exploring for different sized maps, as I often work with multiple zoom levels.

2. I can verify that there is a bug mentioned in MCPE-17647, MCPE-18393, MCPE-18751, and MCPE-18764 is definitely reproduceable in MCPE Realms 0.16+ (survival mode, iOS 10, iPhone 6s) where the maps change location (or are rendered useless) upon resizing. Also, even with a compass added, all marker locations are not visible on the map. Steps to reproduce:
a) create map. look at it - it will be filled or mostly filled. b) place anvil c) add compass d) resize map. look at it - completely blank, including current location and no location marker. This completely breaks the mapping feature.

Persists in 1.0.0

I tried this with both compass empty maps and regular empty maps. Interestingly, when at zoom 1 there was no compass marker, and the map was blank, but when I zoomed out to zoom 4, the compass marker appeared, and the map, created around (-1100, -700) was centered around (0,0) (with the upper left anchor at (-1024, -1024), not (-64,-64) as is usually the case). I created another map in a different sector, (~1400, 73) and it re-centered to the exact same location after resizing.

Update in 1.0 MCPE Realms.
Zoom zero maps work fine, and you can add compasses and rename them. When you resize to zoom 1, they are blank, to zoom 2, and they get changed to center on 0,0 regardless of where they were created or resized (which is odd because at that level, the map with 0,0 should center on 128,128). Resize to zoom 3 and 4, they are blank again. Oddly, in the same seed on single player, the maps work as expected. So the only useable maps are zoom zero, and one location of a zoom 2 map.

(There is a change in single player creative mode from earlier versions 0.14 and 0.15 where taking a map off an item frame destroys it when it used to let you pick it up, giving you one in your inventory (or two if you just placed it). This can be annoying, as it is easy to destroy your work if the map on the frame is your only copy. Similarly, when you click on an item from the block menu, if you have a map in your hand, it will destroy/replace it, instead of shifting it in your inventory. The workaround is to empty your hand first, but it is annoying and I lost several completed maps this way. I mention this, but don't know if this issue is tracked elsewhere.)

I think what's possibly happening is you are travelling too far away form the origin when zooming out the maps. Maps don't zoom from the centre as you might think. They follow a format so they can be placed in item frames and link together. Have a look at the screenshots and comments in MC-64909 - it's explained rather well there.

If you think there's still an issue with MCPE maps then please comment.

(Please see attached photos)
You will notice the anchor point of the four points on the local is at (-64, -64) in the harbor with the small + sign), as it should be. On the Realms map (and this map is exact map that every Zoom 2 map (regardless of origination) re-centers to and is the only usable zoomed map, as zoom 1, 3, and 4 remain blank (possibly recenter to distant as-yet-undetermined locations?)) you see the center is at (0,0) - the small point at the bottom of the peninsula. This is incorrect: it should center at (192,192) for most of that region. Seed is 3440988.

This is getting frustrating. While, Mega_Spud, I agree with your assessment on what the OP wrote, for whatever reason, a very serious yet different MCPE Realms issue has been assigned as a duplicate to this issue, probably because of the discussion here in the comments. There were multiple reports (MCPE-17647, MCPE-18393, MCPE-18751, and MCPE-18764) of the very broken maps that more correctly describe the issue, and technically it appears to be a separate problem from what the OP described, but it looks like it has been decided to try to resolve those problems here. Please see my comment above from 28 Nov 16 above.
Since 0.16.0 we have been having this problem. It works fine in local PE, but not in the MCPE Realm. I described the issue as described in 1.0.0 in detail on 3 Jan 17.

I have attached files that illustrate the difference between the broken MCPE Realms map and the perfectly fine (except for the framed map green dot icons turning to black dots upon reload) local MCPE maps.

I am the cartographer for a 50 or so person Realm, and I am experienced with maps. This has made things very frustrating, since zoom 0 maps are difficult to use for mapping large areas.

The problem is not the centering. I originally expected that to be different, but once I understood how it worked, it made sense. That isn't the issue, at all. The problem is that the map data is reset when it is zoomed out. It doesn't matter where you are, it doesn't matter which zoom level. All data vanishes once the map is zoomed out. It is pretty simple to repro, have a level 2 zoomed map, explore it entirely, then zoom it to level 3. You'll see that previous exploration data is just gone. See the screenshots above. In one instance, the lake is visible, in the next, once it is zoomed, the lake is gone.

The problem of the centering described in the comments above is a different problem, it should have a different issue tracking it.

Specialistol -
You are right that these are two separate issues. I personally think that MCPE-17647 should be the official thread for my complaint, if it can be reopened and my comments transferred there.

Regarding your complaint, I do not know if Mojang considers it a bug or a "works as intended." I thought I read documentation that a map lost its data when zoomed out, but cannot find record of that now. I agree that a map should keep data when zoomed. In reality, if you added paper to an existing map, that is what would happen.

To the moderator/admin - can we separate these issues and reopen the MCPE Realms map issue?

Intended. See MC-883.

Please reopen MCPE-17647. It is not a dupe of this problem.

So, Let me get this straight. Works as intended???

You disable coordinates, then you will not allow us to make a large map in one shot, PLUS you will not allow us to enlarge a map unless we have opened it?

That means we must either make a very large map and explore past the edge so we are sure we are in a new area..., or we must waste maps until we guess correctly? Coming from xbox one edition of Minecraft this is a bit crazy.

I can see why my 13 year old great nephew has quit playing. (He got me started several years ago)

I don't accept this as being resolved. This is very poor implementation. Remember, this is a game, if it isn't fun people will quit.