I've removed the switches from the network and back to inventory, and back into the network. This removed all the switchport configurations and moved them all back to trunks. I've also changed from using static IP for management IP back to DHCP. Still to same problem. This is actually a pair of switches and the last thing that changed was creating them into a stack. I have also tried remove the stack config, physically removing the stack cables and factory resetting each switch individually, then try to form the stack again. Still the same problem. Support are in the process of issuing an RMA.
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