This bug doesn't appear in any older snapshots (I believe)
The sign randomly plays the same animation rapidly, but if you move and place the sign, you start to bug out.
MC-118024
Placing Sign Bug
Resolved
Duplicate
0
uci4$kfcmIde9
(Unassigned)
Unconfirmed
Minecraft 1.12 Pre-Release 6
Retrieved
All particles are also oscillating