How to grant Logic access to the microphone, when Logic has not requested it

Mac mini 2018 running Sequoia

I've downloaded a trial of Logic pro 10.

I have a (new) Behringer umc204hd interface, plugged into an amp connected to speakers.

Signal is coming into the computer - it can be seen fluctuating in the Settings - Sound - Input window. But the signal is not registering in Logic (or Garageband or Audacity).

Logic Audio recognises the interface, and signal registers on the interface hardware, and can be heard through the speakers.

The software is set up correctly EXCEPT that I cannot allow Logic (or Garageband or Audactity) to access my microphone because there's no prompt in the Microphone section of Privacy and Security. If there's nothing in that column - a glorious blank - I can't tick it.

I've tried resetting the microphone through Terminal then restarting.

I've tried de installing and re installing Logic Pro Trial.

I've tried creating a new user account.

I've tried resetting Logic preferences.

I've tried cancelling core audio, restarting and restoring it.

I've checked that the interface and its cable work on a friend's Apple mac recording set up (in which Logic does have access to the microphone.)

Access to the microphone wouldn't necessarily solve the problem, but I presume that no recording software will work without it!

Please help.