I think I have it sorta figured out.
For some reason you have to keep selecting 'squad" or "mission" on radio 5 in the dropdown.
I think it should keep these settings, but I have to pull up the radio menu, then select "squad" or 'mission" and then the F12 seems to work.
If i close this screen, I have to set squad or mission again, even though it already shows squad or mission selected. Once it is selected again, I can talk.
What a pain.