In case it matters, I just installed 11.7.4 on my MBA M1. I don’t know if the problem with Contacts started earlier or at the same time (or in the few days since); I rarely add a contact. My contacts are in my iCloud account only.
It used to be that I could select a group, then click the ‘plus sign’ in the contact pane, and a new contact would be added to the group and I could edit the information in the new contact. Today, after I click the plus sign, I get a new contact and somewhere between about 0.5 and 4 seconds (it varies) to edit it before it vanishes and I’m dropped into a contact in the group I had selected. The new contact, with whatever information I was able to enter before it vanished, is available in All Contacts, but cannot be moved (dragged and dropped) into a group. Any suggestions? Thanks.
Edited to add: I quit Contacts, restarted Contacts, and was able to drag the new contact into the appropriate group. I’m still interested in what went wrong, but since I have a sample size of one and the problem is gone, I don’t expect anything. Adam, feel free to delete this post.