MacBook Pro, LG monitor connectivity issue

I was using the LG 27" Ultrafine monitor with my old 2017 15" MacBook Pro for four years. Got a new 2021 16" MacBook Pro in April, and it was working fine till about 2 months ago. After the latest Monterey updated, it does not even show up as a display. Took it to the Mac Genius bar at the store yesterday and they spent an hour on it but were not able to figure out the problem. Say that they are unaware that it is a Monterey issue. The monitor worked fine in the store with an 2020 MacBook that had Sierra on it. Has anyone had a similar problem? Is there an easy fix?

Thanks!