This seems to be related to my account as I have a both a desktop and a laptop exhibiting this behavior.
Basically, it matchmakes but never loads the preview image for avalon and the 5 second countdown never happens. I just get stuff on "Match Started. Loading level" while my party loads in fine.
I see one other post about a similar issue but not finding anything that works – I updated drivers and disabled some other applications. Cleared DNS and tried a different network, nothing seems to work 🤔