Well, I'll be jiggered.. it worked!...At McDs in southern OR.
I turned all the stuff on, then held the phone at several different angles. I was about to give up when I tried clicking open the 'tap and pay ready' choice within the wallet app - the line that shows me the CC I have on file.
Then I tapped the top of the phone at a 45d angle to the reader.. and voila.. bells and chimes. Yahoo. Phone still has case on. And it withdrew from my cash balance as it's supposed to. Not sure exactly what I did, whether it was the manner in which I placed the phone, or opening that final window.
Time will tell. Thanks for all the help.