Same issue here with Cardo.
The solution was found in another forum where someone explained that you need to switch on recording on Bluetooth on the official voice recorder to be able to use your Bluetooth mic to give command.
Anw, Nothing phone seems to outsource their “Support Team” from abroad and they had noo f8#king clue. Pretty useless, but really good at confirming that your matter is raised with the relevant team. My matters been a year with the relevant team now and they haven’t fixed any problems.
Just a rant sorry, please let me know if anyone can help with Cardo issues. Maybe the relevant team is you guys 😘