TRADOS 2021 "no results available" for more than half of the segments (though they have terms from my Term Base)

I am working with TRADOS 2021 and in my Term Recognition, I get the message "no results available" for more than half of the segments (even though they have terms from my Term Base). Some segments work, but others don't. When I try to "quick add new term", I get the message "the selected term already exists in the active termbase", but it doesn't show up in my Term Recognition. I have restarted TRADOS numerous times, reset the window layout, and removed and re-added the termbase. Any ideas on how to solve this?