Can't add contacts to a Group, nor can I create New Contact Cards.

I'm using macOS Big Sur, version 11.7.10 on MackbookAir.

I learned from other conversations to Click the name I wanted to add to a Group , then- hold Shift- while dragging it to the desired Group. This worked for most of the contacts, but some just refused to go. Weird, cause I thought; I don't even like some of these people. So I fantasized the Universe was trying to protect me from them...Never mind...

So, I thought, OK, just create a new contact for the stubborn ones. But No, after opening a new contact page, it (the New Contact Page) would vanish in about 12 seconds, and I'd be left with some random other contact staring at me. Creepy, cause they're the judgemental ones. lol

After a few colourful words and a chewed upper lip I thought: 12 seconds gives me time to type in at least 4 letters, then quickly hit Done, hoping I could return and edit, simply changing some of the context in the notes area to as not be exactly the same; Im sneaky that way.

And It worked. That only took 3 hours out of my day.