[T-Mobile Galaxy Note 4 Q&A, Help & Troubleshooting] ajm786:
Update:

Finally, some closure on this issue.

After EXTENSIVE research (probably one of the few times that I used every Google trick in the book), I found this post, which basically described my issue to a T. Needless to say, it emboldened me that it was not any issue with my device, ROM, or configuration, especially being that Google Wallet set up tap to pay perfectly.

http://xdaforums.com/nexus-4/general/google-wallet-fix-t2096956

I set back out on the road, and this time used MasterCard Contactless locator to find an actual store that offered tap-to-pay.

http://www.mastercard.us/cardholder-services/paypass-locator.html

The first place that I hit on that list was a Shoppers Food Warehouse. Unfortunately, that store either didn't have it turned on, or the cashiers were clueless. Probably both, because when I went up to pay with my smartphone, the cashiers looked at me like I was from a different planet. Needless to say, that didn't work. So I left for my second store on the list.

The store was a Panera bread place. I stopped by and got a cinnamon roll. The cashiers assured me that their tap-to-pay was working, and hit something on their end so that the touchpad was waiting for input (either tap or swipe). So I unlocked my phone, unlocked the Google Wallet app, and hovered over the touchpad, which clearly had a Paypass logo on the upper left hand corner of the touchpad. After hovering all over the touchpad (this took about 30+ seconds), the phone finally registered, but it was an error:

This time, I flipped the phone around so that the battery side was up (NFC is on the battery) closest to the Paypass logo. After hovering CLOSELY and nearest the vicinity of the Paypass logo on the touchpad for about 5 seconds, the phone finally buzzed, and a W appeared on the screen. The cashier hit something on the register, and what do you know: IT WENT THROUGH! Here was the confirmation!

After all this ridiculous hassle in trying to find out whether or not tap-to-pay works, I can confirm that it actually does. However, during this ordeal, here are a few observations I came up with.

1. Finding a place that does tap-to-pay is much worse off than 1 year ago, which is when I last used it. All the places I went that used to accept it (CVS, Home Depot) don't accept it anymore, just because of the stupid issue with Apple Pay.

2. Not only do you have to find a place that offers it, the cashiers have to know what they are doing, otherwise it will never work.

3. For our Galaxy Note 4s, the NFC is VERY PICKY. I'm guessing it's because the NFC chip is so small, and the fact that it is shoved over to the right side of our big phones doesn't help things at all. This is the reason why I was getting the "last tap not successful" error message so frequently, because it has to be in the right orientation, and it takes more than a few seconds for it to register.

4. The face of the tap-to-pay surface, if the clear glass type, has to be CLEAN and free of obstructions. Part of the reason I was having issues at the Panera bread is because the Paypass surfaces they had are laid flat rather than at an angle, so they were very dirty.

Bottom line: Google Wallet Tap-to-Pay works fine on AOSP/CM12 and the Note 4, if you have Google Wallet set up properly and it says "Read to tap and pay".

I hope this helps anyone else out there who is having these issues.