The bug
When breaking the half of multi-block block (e.g. doors, beds, double plants) on which a block, such as a sign, a button, or a torch, is not placed, that block will break without dropping as an item.
To reproduce
Place a door
Attach a sign (or a torch, or a button, or any other block that requires support) to one half of the door
Break the half of the door that you placed the block on
→ ✔ The attached block breaks and dropsPlace the door again
Attach a block to the door again
Break the half of the door that the block was not placed on
→ ❌ The attached block breaks, but does not drop
Linked issues
is duplicated by 15
MC-143807
Blocks attached to beds do not drop if you break the other side
Resolved
MC-151071
Doors/Beds can make some things to disappear
Resolved
MC-153572
Breaking bd not dropping side block
Resolved
MC-154947
Signs attached to front and back of doors get deleted when door is broken.
Resolved
MC-158182
Placing Things On Door And Item Disapear!
Resolved
relates to 2
Attachments
Comments 12
Affects all "multi-block block" (maybe there is a better term for this). Resolving the other reports as duplicate of this.
Isn't this intended behavior, considered signs have to be mounted to something? You can't have a sign just floating in the air without some sort of support holding it up. Think about when people use signs to hold up water. Signs have to be placed on signs or other blocks so they stay up. Also, the signs aren't deleted, just broken, unless you are referring to text on signs, but text doesn't stay on signs when broken with a tool, so I'm guessing you aren't saying that's the issue.
Just realized that the signs/torches are not just broken, but completely disappearing. My bad.
boq
Breaking the block where the sign is at also breaks the sign