Impossible upgrade firmware ur24c in Mac Mojave

good morning gentlemen of steinberg
I bought a UR24C 2 weeks ago
I only mounted it today because I was waiting for the MAC 15 (2015) - 16 gb - 1Tera ssd - Mojave last vers. - on which I have installed cubase 11 pro
After completing the specific software installation I verified that the UR24C is recognized BY THE SYSTEM exactly as I read in your instructions. all right
but here the problems begin.
the card firmware cannot be updated.
An error message appears
“error: ur is not detected. please check the connection and reboot this software”
I know the firmware upgrade procedures. I know they are delicate. i also have steinberg CC121 controller which requires similar installation method. so everything was done exactly as per instructions.
I also tried to update firmware via iMac (my studio resident Work Station) with the same result:
“error: ur is not detected. please check the connection and reboot this software”
Also, the standalone NuGen Visualizer 2 software cannot detect the sound card correctly
The card appears in the list but is not monitored by Visualizer 2. Sign of malfunction
I am writing today a few days before Christmas hoping to have an answer before the summer.
I’m waiting
(I’m increasingly afraid of Steinberg’s products …)

(P.S. EAST WEST / SOUDONLINE REPLIES IN 45 MINUTES !!!) UR24C REGISTERED DOES NOT APPEAR IN MY PROFILE