Waiting for connection Big Sur 11.3

Hallo,
Before updating to Big Sur 11.3 my CNC (3018Pro with grbl 1.1 f) worked well with LB 0.9.24.
Now I get no USB connection (waiting for connection). Big Sur says that I must remove accessory with too high consumption to reactivate USB. I connect a USB-hub with external power but with no result.
Back to LB 0.9.23 give me no results also.

What can I do to connect my CNC with LB?

I found the problem. Disconnection in one of the limit switches.