It’s work for me too without extension cable for the moment.
I just stop my Raspberry, plug the dongle and start my Raspberry and it’s ok…
Before I tried without stop the raspberry, I think that was the problem.
I had the same issue: only SSD works fine, inserting sonoff dongle resulted in the error message “Error: network commissioning timed out - most likely network with the same panId or extendedPanId already exists nearby” in the zigbee2mqtt log files.
Checking the link in the log file (Zigbee2MQTT fails to start | Zigbee2MQTT) this would refer to a power issue with the advice to use an external powered hub for the SSD.
I tried the extension cable for the sonoff dongle as opt-ed by several people, and I can confirm this solved the issue for me.
that was my problem too. The screws are so tight. I cracked them with sheer willpower.
Supposedly there is a way to put it in bootloader mode with a linux program without pushing the button.