Forge version: 14.23.5.2846 (Bug exists in 14.23.5.2838 as well)

The short version is, blocks which do not take up a whole block (I'm uncertain of a better word for these) are deleted/disappear when the hose is used on them with spill mode on.

The block in question is replaced with the liquid from the tank- Water in most cases as I most often manipulate water. Vanilla blocks this includes are slabs, end portal frames, fences, stairs, hoed soil (Sometimes I have to shift-click to make that happen, sometimes I dont.) and chests, as tested in creative mode as I'd rather not lose a chest in this matter. This happens in singleplayer worlds and multiplayer servers. The desired effect is, of course, merely placing the liquid in the adjacent space to these blocks, as would work with a water bucket. I hope this is a sufficient bug report.