Sometimes you are unable to place blocks near fences/walls/hoppers

 I know this issue is present since at least 19w06a, but couldn't find any report about it.

You are unable to place blocks in certain locations adjacent to fences and walls. I have no information concerning the cause of this issue, it seems to be occuring randomly, although I might be wrong here.

It happened to me a few times, but I recorded only one and attached it below. Please note that the fact that the slabs disappear after a certain period of time is due to server lag, not the issue itself.

2019-02-21-2206-01.mp4

Edit: I am able to place torches in the spots where I could not place slabs in the video