I have the same issue as you when running ios xe 16.9.1 with Mitel phones. When the main load of the phones is at 06.02.00.01 dhcp will not work. If you upgrade the phones to 06.04.01.07 it will work. I speculate that the phones are dropping the D...

You need to map the service instance to the bdi interface.  Add the command bridge-domain 1 to the service instance configuration.

You need to map the service instance to the bdi interface.  Add the command bridge-domain 1 to the service instance configuration.