I went to place down a bucket of water in the nether, and it took my water from the bucket and did not create a source block. I went into creative mode to try and it still did not work. I tried placing on different types of blocks, no result. I used the /setblock command to place a water block on the ground, and that worked. The water did not flow, but after about a minute it started to flow? It may be lag, but it is still a bug. Thanks!