I have a mixture of juniper EX4500 with EX4550, today the would be backup routing engine isolated itself from the virtual chassis and was showing up as master.
Problem or Goal:
Backup routing-engine isolated itself from the VC and was showing to be master.
Not yet sure what could have caused this.
I powered off the would be backup routing-engine (EX4550) and powered it back on, it managed to join the VC again, but took up the master routing-engine role.
1. Resolution Guide - EX - Troubleshoot Virtual Chassis (VC)