Hi,
I took my mini out today and did not seem to connected to the remote, never had that problem before. So after a bit of messing about, I found a fix. So to save someone else  pain....

Just a tip if you can not connect to the remote after updating to MIUI 12. I did all this, but some maybe not needed.

Remove app and reinstall, and say Ok to all access settings it requests. And in app settings set battery to "no restrictions ".

Go into developer mode. Settings >  about the phone > MIUI vwesion a (tap 4 times to enter Dev mode).       - not 100% if this is needed.

Settings > Additional settings> Developer settings > Default USB config >  Transfer photo's (PTP).


I also enabled  access to any USB things, in Dev settings, but I don't think that mattered.

Have fun,
Neil

Hello there Neil. Thank you for reaching out and sharing your experience with regards to this matter. Again, thank you for your support and fly safe always.