The bug
When placing a block in a spot that an entity is just passing through, the block disappears after being placed, but the player's inventory is not updated properly. A desync occurs when the player tries to place a block at a location where an entity is just passing through it.
Original description
On 1.14.4 I've noticed an issue where if a block is placed the exact moment that an npc walks into the area you are trying to place in the item will disappear. The item will not be returned to the player's inventory, it'll just vanish completely.
This has happened around 3 times, all these occurring when I try and place a lectern and a pesky villager walks onto the area I'm trying to place in.
Unfortunately I don't have any logs for extra information but I hope this was helpful in some way.
Linked issues
is duplicated by 33
MC-271960
Blocks disappear when placed if mob walks on the same block
Resolved
MC-271505
When a block is placed in front of an armadillo with a 45° incline, it disappears
Resolved
MC-267884
Lectern becomes invisible in inventory
Resolved
MC-267139
Mobs destroy blocks whenever you place a block where they are walking.
Resolved
MC-134866
Slabs and stairs disappear when placed quickly under falling sand.
Resolved
relates to 2
Attachments
Comments 8
Duplicate of MC-95720
It is still in your inventory, just click on all of the empty spots till it shows up. This has also happened to me.
Can confirm. Can't believe I can't find an earlier ticket about this.