Great it was solved. It seems X-T4 is little "tricky" about SD cards, I have a common problem - I almost always need to insert the SD card(s) twice before Card Read error is is gone (yes I use Fujifilm recommened SD Cards, Sony UHS-II V90).
Anyway this is what is said in X-T4 user manual, Troubleshooting section about the error You had (same suggestion for all 3 errors):
FOCUS ERROR,
LENS CONTROL ERROR or
TURN OFF THE CAMERA AND TURN ON AGAIN
Explanation:
Camera malfunction. Turn the camera off and then on again. If the message persists, contact a Fujifilm dealer.
I would have contacted Fujifilm support if the problem had persisted.
Have a nice day and I hope Your X-T4 will work fine for You now and in future.
I have X-T4 also (I had a lot of trouble with it first and it was a "lemon" and I got a new and it has worked fine).
/Bo
