If you place a sign and then place another sign on the front of the first sign, then any block that was in front of the first sign will get deleted.
Linked issues
duplicates 1
Comments 2
On further analysis, this is the same bug as MCPE-102371, so I am resolving this report as a Duplicate.
Video shared on the Mojira Discord: https://discord.com/channels/647810384031645728/648555681397342228/764722413840891934