I have just re-flashed Buster and installed Build-a-pi. flrig can't configure the USB port with error "Transceiver is not responding"
I tried flrig on the laptop and all is OK.
ls -sal *USB*
0 crw-rw---- 1 root dialout 188, 0 Sep 7 10:10 ttyUSB0
pi is a member of dialout group. I've never seen this behaviour before.