You need to make sure PulseAudio believes your device is connected - even if you think it is.
Run the command bluetoothctl and look at the devices connected. I have 2:
[NEW] Controller 00:1A:7D:DA:71:11 Hairy16 [default]
[NEW] Device E8:07:BF:12:FA:4A AUSDOM AH861
[NEW] Device 90:B9:31:77:B7:78 Tim's iPhone
type the command connect <ADDR>, where <ADDR> is the 12 letter address of your device - e.g. E8:07:BF:12:FA:4A. You should see the following:
[bluetooth]# connect E8:07:BF:12:FA:4A
Attempting to connect to E8:07:BF:12:FA:4A
Connection successful
[DEVICE NAME]#
Then you can change the profile successfully.
bluetoothsctl devices– Marcin Orlowski Jan 30 '21 at 18:46