I put glowstone one layer under the water in the village well. When I accidentally placed an extra glowstone on the first layer of water and then deleted the glowstone, the water disappeared, but the water next to the empty square did not run in to fill it.

I deleted another water square next to the first the same thing happened and now there are two stationary water blocks and two air blocks in the well.

When I poured water in the empty square the water returned to acting normal.

When I tried to repeat the water bug in the same place and a different place, it did not happen again.

I recreated the same world and tried the same thing in the same well and this time it did happen again! I was able to delete three of the water blocks leaving a single block of water just sitting in the corner. But again when I refilled the well, the water returned to normal and I could no longer repeat the bug.

Possibly something to do with generated water vs placed water?

creative, beach, village, seed: -8300275442758179407, x/y/z: 275/63/-249