Water does not flow sideways when there’s no block below it

Can confirm, tried to fill a space with water and noticed it would not spread but stay in that form.

New water source blocks only generate when solid blocks are directly below. Like in your picture, the water "holes" are only in deep water.

That’s not the issue here, the issue is that water doesn’t start flowing at all.

It flows on solid blocks. Just empty a bucket on land. You can create 1 block deep lakes without a problem.

Also it appears to have very random behaviors in general, in this attached instance it split into a v instead of spreading like it used to.

That’s a different issue. (MC-76857)

Water source don't flow to the sides when there's falling water/another water source below the source.
Visible when placing water on the ceiling - it will flow to the bottom creating 1-wide waterfall, but don't flow to the sides like before creating cross-shaped waterfall.

If I pick up water in a bucket that has a water block beneath it, it leaves a hole in the water body - ie the neighbouring water blocks don't flow in to fill it. It works as normal if there is a solid block beneath it.

Here the water should flow also (tested on 18w19a)

Confirming, with image, that issue persists and is repeatable in 18w19a

Confirmed in 18w19b

Confirmed in 18w20a

Confirmed in 18w20b

Possible related bug: MC-129899

Related to this, in 18w20c, if you place water on top of a sign, bottom slab or stair (say at the top of a water elevator or in a water escalator) the water will not run off of the block above the sign, slab or stair (did not test this with other blocks). This makes water elevators and escalators rather useless (aside from the fact that many mobs like skeletons and the various versions of zombies no longer swim up the water elevators).

It does not seem to matter whether there is a block or air next to the sign or stair (note: water flowing to the stair in the image below properly flows up to the water source on top of the stair).

Confirmed in 18w21a

Not sure if this is related or a separate bug: I noticed in 18w21a, "natural" water source blocks will not spread horizontally more than one block.

"Natural" sources being those generated with the world, or formed by normal source-block-on-two-sides water mechanics. Source blocks from water buckets, or those containing sea grass, waterlogged blocks, etc are not affected and behave normally. I did a little other testing, and found that a single-block source in a cave was unaffected, but water in a subterranean lake was.

Separate bug.

Confirmed in 18w21b

Confrmed n 18w22a

Confirmed in 18w22b

I can't reproduce this in 18w22b.

@unknown I could reproduce it in both Creative as well as Survival mode by clicking rapidly with empty waterbucket(s), see:

Edit: Upon relog, those water holes are gone though, maybe just a visual glitch?

Because I stuck my head into one of those water holes in Survival, bubbles go down as if it were water, as opposed to that bug in previous snapshots:

I can still reproduce in 18w22b, make sure there's not a block below the water source.

Also reproducable like so:

As one of the early bug reporters in this issue, I would like to say that as far as I can see in 18w22c it appears to be fixed in single player. I reproduced the exact same issue and the water filled up the hole. There may be a similar bug thats not resolved, but the one I submitted is. Thanks.

Okay, so. The initial problem I found where breaking blocks on top of water created a hole has been fixed. This is the pic I posted when I found the problem:

Now when you break blocks that are sitting on water it fills in as it did previously.

However there is still a bug of some sort messing with the water. I believe it is this bug, which I reported as well: MC-129899

If you place a torch in the water with a block above it the water disappears and the torch stays in an air bubble. If you break the torch the air bubble remains. If you break the block above the bubble the water will fill in.

In addition to this if you have a two block wide body of water and you break one or two blocks at the end the water will not fill in. It doesn't happen when the water is three across and you break all three blocks in a row. It also doesn't happen if you break the center block. But it does happen if you break the end blocks and leave the middle block intact.

Confirmed in 18w22c

Affects 1.13 pre-release 1
I was making a water tank and the second or higher layers of water do not automatically fill in like they used to.

Confirmed in 1.13 pre-release 2

I've been observing this for ages already. Always thought it's WAI.

This is definitely not WAI.

It seems that it doesn't occur with colum bubble affected water because that flows normally 

The problem is still here in 1.13-pre8.

Confirmed in 1.13pre8

This issue is already been fixed. We will need More than a dark screenshot to reopen anything.

Does it stay that way after relogging? If no, it's seems more like MC-12363.

No but those mountains of water are still there after i relog. I don't know if that is working as intended but it seems really weird.

Well, buffet worlds don't guarantee sane results, especially if you try to do deep-ocean nether.

This might not be part of the the issue but I sometimes get one block air pockets in water if I keep using the empty bucket on water in creative mode fast enough.

That's MC-12363 (or a variant of it).
Removed all screenshots that are actually MC-12363. and not this issue.

Still in 19w08a

That screenshot doesn't describe this issue. If you think this is a new bug, please create a new ticket. Apart from that, unless I am mistaken, this is how water physics work in Minecraft as far as I know.