Trash and Junk email folders

I recently updated to macOS Big Sur 11.0.1. My trash and junk folders moved from my Favorites to On My Mac and are now listed as "Trash - On My Mac" and "Junk - On My Mac." Problem is there is nothing in these folders. No deleted emails appear in Trash. They just disappear. There is nothing in the Junk folder either. How am I supposed to see if emails accidentally appear in the Junk folder if they're nowhere to be found? And how can I recover a deleted email if they're not showing anywhere either? This is a serious problem!! Please help!!!!!!!!!! Thank you for your time. Catherine