...etc. just says in all 3 modes (P,S&C) that "this function unavailable in this mode).
Any ideas?

Hi. I am sorry for the trouble that your DJI Mavic Mini has caused. With regards to the said issue. When you are trying to initiate the Circle or Helix on the DJI Fly application are you seeing like a letter P on the upper left side of the screen? If not, please try to tap the letter you see on the upper left corner until it show the letter P for P mode then try the intelligent flight modes like Circle or Helix. If issue still persists, kindly please post a picture of the said issue. Please keep us posted for further assistance. Thank you.

Tried all modes, including P

does it work for you to automatically create videos with those you have just recorded?  to me it always says invalid format