We have a mixture of 3825 and 3715 APs . After upgrading to v10 software we updated the AP firmware as usual. Trouble is we can get all 1,037 APs up to v10 firmware, wait a few days, and about 4 APs will show up with v9 firmware. Wait another day and the number jumps to 7. The same 7. I can set for Controlled upgrade, upgrade these 7, ssh into the AP, see it has v10 software, reboot, log back in to verify v10 software. I can set the controller to "Always Upgrade APs to default image" which is v10. No matter what within a couple days an AP or 2 show up with old v9 firmware. APs I have ssh'd into and seen the v10 as well as having the controller list them as v10. This cycle of events has repeated 4 times in the last 10 days.
It is as if they are factory resetting themselves for some reason. Does anyone know what is wrong? Are they just bad APs that need to be RMA'd?