We're testing VOIP phones with ISE. ISE detects the phones by MAB and places them in our Voice VLAN with a DACL for security, this works fine.
After the tests I configured the port to a non ISE port (default interface) and added the normal working configuration.
Result is that the IP phone doesn't get an IP address. If I plug the same phone on a different interface on the same switch it's working again.
I have no idea why this strange behavior occurs, maybe someone can help me out.