My device is an iPhone SE with iOs 11.3. I’m on the latest version of the Blockheads, and this was on a custom single player world.
I wanted to test to see if one could plant kelp on an ice block. The environment is hard to get right— you have to have the ice’s environment be cold enough to keep it frozen, but the block directly above it liquid.
I got the conditions right. The ice block remained frozen, and the water block would stay liquid.
I then tried to plant it by tapping on the ice block. My blockhead “planted” it— I lost one kelp in my inventory when the action was completed, but there wasn’t kelp planted.
I don’t doubt that this isn’t a high priority bug— the conditions are hard to get right.