Interesting question, I followed this guide:Silly question but...
Did you flash the zigbee version of tasmota or regular tasmota?
Also in zha mode you need yo force channel in home assistant. If you change it from default you need to pair devices again
Check out these two videos we did on Zigbee fundamentals - Video #1 - Video #2 I reviewed the Sonoff Zigbee Bridge a few months ago in a...
I think the last upgrade in the doc switches it to regular tasmota
Edit: Just check and I used tasmota-zbbridge.bin for my firmware upgrades.