Even if user setup to specific brand,
if you try to login as user, it will drop you to kb of default brand.
my primary brand on support.brand0.io and additional brand support.brand1.io
if i try to login as user from agent interface, it will always drop me to support.brand0.io
Login as user works only to for primary brand - انتقادات و پیشنهادات / Bug Report - Deskpro Support
We've noticed the same behaviour, you can work-around this by accessing the agent interface from support.brand1.io and then impersonate the user.