How can I move a contact to another group

I have a Mac Mini M2 running Sequioa and want to move/delete a contact from groups. I am sure I have done in the past, but can't seem to get it working. There is a *Remove from group* menu, but it is greyed. On my iPhone there are options to *Add to List* but not on the Mac. ---------- I had added a contact in Mail (which showed under All Contacts) but was unable to drag or move to my Personal group. I also tried to move a couple of contacts for people who had died. Both of these failed. I restarted Contacts, and later rebooted the Mac Mini but was still unable to move. Later that evening I found the Contacts Edit option worked. This morning on booting the Mac Mini I was again unable to move. Any ideas WHY or how to force the option.