When an iron trap door is placed onto an already powered block, it does not retract.
Comments 4
It isn't intended. I can confirm. It happened to me. I was just about to report this bug when I saw this report.
This affects the wooden trapdoor and wooden door too.
In all cases door/trapdoor wood/iron a block update causes the door/trapdoor to change to the powered state.
Additionally with the wooden door/trapdoor it can be put back to its unpowered state by clicking on it.
Duplicate of MC-2298 - If you have not, please use the search function in the future, to see if your bug has already been submitted. If you could not find the original report, please comment with the keywords you searched for.
I think this is intended. Iron door acts like that too.