When you step on a pressure plate with an item frame inside it, it doesn't deactivate.
To recreate this bug, you have to place a item frame on any block/stair and place a wooden pressure plate in the same block, lastly you step on the pressure plate, then you can see that the pressure plate remains activated forever.
Thank you for your report!
We're actually already tracking this issue in MC-152273, so I resolved and linked this ticket as a duplicate.
If you would like to add a vote and any extra information to the main ticket it would be appreciated.
If you haven't already, you might like to make use of the search feature in the future to see if the issue has already been reported.
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