I'm looking into this for you. I did verify that things look to be okay on our end, but I flipped a couple of switches off and on for you (the Ting equivalent of 'Did you unplug it, and plug it back in?') just in case.
If that didn't fix it, reply back to one of the support emails you received asking if it can be escalated to our network provider to investigate why WFC isn't working on your G6. It's on the supported list, so it should.
Before they get back to you, you can always also try clearing data for the Phone app. Here's how you do that. After that, reboot and see if your phone can connect to WFC, or if it still spits up the REG 99 error.
I'll be monitoring this thread just in case you're still stuck and want me to dive in and help the guys figure it out.