The AP's probably have stopped sending LACPDU's to the switch. Maybe if you reboot AP it will work again.
If you need to confirm the AP is sending LACPDU's you'll need to capture them from the switch.
The AP packet capture on the wired interface only shows the LACPDU's coming from the switch.
You'll need to confirm they are both sending them.
The destination MAC address for LACPDU's is 01:80:c2:00:00:02 so the ether host 01:80:c2:00:00:02 for the capture.
The actor ports of the AP will be labeled 1 and 2.
The switch in case of a stack will probably have higher numbers.