Contacts for Mac: Dragging contact to list
I created a contact on my Mac in the Contacts app.
Within the same account (iCloud) I have a list. It is not a smart list.
I try adding the contact to the list as follows:
I click the card in the middle pane. It turns green.
I drag the cards from the middle pane onto the list-name. The list-name turns green.
I release the card. The card fails to appear in the list...
Oh Wait. After the above procedure resulted in a failure about TEN TIMES, the last time it worked.
This procedure is not complex so I was not doing it differently all but the last time.
The same procedure resulted in two different outcomes.
What is going on?
iMac 24″, macOS 15.7