This has been a major headache as I thought it was a theme problem!
Run this query in phpmyadmin in your wp database as suggested by https://www.jauhari.net
“UPDATE wp_term_taxonomy,wp_terms SET wp_term_taxonomy.description = wp_terms.name WHERE wp_term_taxonomy.term_id = wp_terms.term_id”
but make sure you are using the wp prefix or change it in the query the prefix to what you assigned.
The query worked for me but when I add new categories , I have to run the query again. Hence, I will just revert back to 2.8.5.