Sean Reid

Still present in 1.16. I was mining, and there was lava falling from the roof. I placed a block to stop the lava, and as it was slowly disappearing, I mined 2 ancient debris, both of which I saw fall into the lava expecting that it should be fine because they aren't supposed to be destroyable by lava, but when the lava fully disappeared, I realized it burned my ancient debris. I saved a video if needed. 

This also happens quite often while mining different ores. I noticed that I could get the blocks to reappear without placing a block by just hitting the use button where the invisible block is located, even say, eating a fish. Hope this helps.