I encountered this problem in a cold Biome. I was trying to "melt" water by channeling out the section of frozen Murky Pool. However I built a floor on top of it to prevent it from freezing after it hit the bottom of my dug out area. Later I removed the floor and channeled around the large block of ice only to find that it was not only not falling and crashing and doing what physics says it should do. But I found out that it was emitting an anti-gravity wave which prevented it from falling. Later when it was summer the blocks of Ice that I did not build floors on/touch/mine/etc melted however the Ice tiles that had the floor on it did not melt. I later channeled them to find out they did emit water once done, but to my dismay I found that there were now not one layer of water but two. the bottom layer composed of 2-3 depth water and the top layer was 1 depth and was able to make the stone from the floors land on it as when (when deconstructed)
TLDR: Try to melt ice with a cave-in
Ice did not cave-in
Ice did not melt
Ice floats
?? ??
Profit
I also have a video of how its set up but I'm not sure where i should upload it.
-DDS
I think i have found the cause. It happens to be sitting on top UNKNOWN tiles. I did manage to create a small cave-in and a bunch of the UNKNOWN tiles removed the 3-4 depth water (its raining now)