I do the consulting for one of my remote clients he is away from my location about 3 hours commute. I got one complaint through email but I am not sure it is relevant for SystemAdmin to resolve. To me, this error seems AutoCAD has corrupted. Please check the below screen after the restart his Menu Bar Ribbon keeps disappearing in AutoCAD.
I took the access through TeamViewer and reinstall the AutoCAD software but that wasn’t helpful even after the reinstall this behavior remains the same.