Ender dragons can break command blocks. A really annoying bug when you have something involving dragons in your command block contraptions.
MCPE-20645
Ender dragon can destroy command blocks
Resolved
Fixed
2
(Unassigned)
Unconfirmed
Windows
Windows 10
command_block, ender_dragon
1.0.5.54
1.1.0.9
Retrieved
I think I know why this bug is happening. Somebody forgot to add command blocks to the list of blocks that the Ender dragon is unable to break. It's a simple fix. Add command blocks to that list.