You should consider opening a TAC Case with Cisco. I had the same issue with a couple of 3802is and it ended up being a bug that was rectified by hardware upgrade. https://www.cisco.com/c/en/us/support/docs/field-notices/701/fn70143.html Let me know ...

Hi All,   I raised TAC and issue was resolved. It indeed was the bug.   Thanks a lot.   Peter

I am running code 8.5.120.0 and also have the same issue with AP3802e.--Peter