I’m having the exact same issue. After working for some time all context menus and drop down menus close instantly after opening them (or so it is visualized). If I actually do a snip of the screen the menu is actually there. I realized this when I streamed my screen for a colleague. He could actually see my drop down menu! While it was gone for me. So I did a snip of the screen (Windows key+Shift+S) and there it was!
My specs:
AMD Ryzen Threadripper 1950X 16-Core Processor 3.50 GHz.
64,0 GB ram.
Geforce RTX 3090
2 monitors:
Primary: LG 38’’ UltraGear 38GL950G QHD+ Curved Nano IPS 175 Hz.
Secondary: LG 32’’ 32GK850G QHD VA G-Sync.