vanishing blocks

Put the summary of the bug you're having here

What I expected to happen was...:
I placed a lecture table to get an librarian so I can buy mending books

What actually happened was...:
A villager walked where I placed the block, I saw it for a couple of nanoseconds, then it just vanished, not in inventory, not somewhere else. 

Also after I posted this I tried sleeping, accidentally pressed on the wall and the table appeared like it was always there. It didn't show it in the inventory tho

Steps to Reproduce:
i dont know how to reproduce maybe try placing a lecture table right as the villager approaches a position