can't delete individual contacts

After updating to Catalina (latest version) I'm no longer able to delete individual contacts from my contact book. When I select the contact to be deleted and press the "delete" key all I get is a clunk sound and the screen flickers. Nothing else. The contacts to be deleted are NOT part of a smart group. I was able to do this at will in High Sierra but not Catalina.

I imagine I don't have it set up right and need some help.

Any suggestions?

Since I can no longer select multiple contacts and drag them to the address box in a group mail with Catalina I have to put together separate "groups" of contacts for group mailings. This is really a pain in the old rear end.