No firmware update, probably just an app update.
I think it is just a matter of hours or days, Winwing updates their software quite frequently.
You can keep an eye on new release here, the release notes get listed here: WINWING
Works perfectly with all three (319,320,321). What I also like about it is, you can open it at anytime, even after loading the sim, and it makes the FCU work.
Why I am very happy with my miniFCU - with Spad support I can do 100% of the control bindings, voices and scripts on my own, for literally every aircraft in the game. May be more expensive but boy is it worth it. Love using it daily.
I’m pleased to report that after coming back from vacation yesterday and firing up the sim, my SimAppPro launched an update and now the FCU is functional.
While not the quickest update, very glad to see them get it resolved in what I would call a reasonable amount of time.