No, Stanley Zhou, T300 mesh AP cannot become Master AP. I don't know "PK" acronym in Unleashed terms either.
Everyone needs to please open individual tickets with Tech Support, and provide your logs and network diagrams.
If this is indeed something with APs going to factory default, it needs to be tracked by Tech Support, who can open Bugs with Engineering.
Please open a ticket with Tech Support, or ask for escalation of your existing tickets if no Bug has been filed on your behalf (yet). Thanks!
https://support.ruckuswireless.com/contact-us