In Unleashed AP, only one way the AP will set factory automatically, that's PK fail (There are two master AP, it PK, then one master will become member AP).
I guess in this case, whether in some reason the mesh AP (T300) gateway is reachable and become root role, then it is elected as master, then come back into the network, it PK by the old master, so it will set factory.
Can you tell me what's Ip configure for this T300? and what's IP configured for the Master AP? please give us the IP, and gateway infomation. SDC will try to reproduce it.
Anyway, in 200.4 patch (18.104.22.168.49) and 200.5 version, we have changed the logic, when Pk fail, if the AP is not gateway mode, it will not set factory, it only reboot. So I think if can customer can try to use 200.4 patch or 200.5 version.