Open PHONE_REGISTRATION_ERROR When setting up newly flashed phone

I could only find one post on this forum about this error but I did find other threads in other forums where it said it was an account issue and to clear data on Google Play Services then remove and add your google account from the phone rebooting between the remove and add. I did that, but it does not seem to help. I have found other threads stating it is a GSM error on the server side, but that was cleared up by a dev or someone at google, maybe? https://groups.google.com/forum/#!topic/android-gcm/7k0pnRDhIdw
I just installed Pure Nexus 7.1.1 on a Nexus 6. Join was working fine on this phone when it ran 6.0.1 a couple hours ago.
The first error:
Error: java.io.IOException:
PHONE_REGISTRATION_ERROR
then it says:
Couldn't register on Join's servers:
Error: java.io.IOException:
PHONE_REGISTRATION_ERROR

I have also tried removing and reinstalling Join, along with clearing the data and cache in join, It does not seem to help.
I am interested if anyone else has run into this, and if so, did they find a fix for it? If anyone needs more info, let me know.
Thanks,

 

I have tried that (it is what I described in the first part of my post ) Though 7.1.1 does not appear to have Google Services Framework. Or at least Pure Nexus does not have it in Apps. I can only clear Google Play Services.
I have done that procedure again, and no changes. I have even cleared cache and data in Join itself along with removing and reinstalling it.
Anything else to try?

 

Yes. Both times.
It was working fine in Stock Nexus 6.0.1, just before I wiped my phone top put Pure Nexus 7.1.1 on it.
I just did this again, and I noticed for a brief moment, there is a toast popup that says "welcome back to Join" with my gmail account email address, then the error pops up. The toasts are different though, different fonts and different locations. They overlap at the bottom of the screen, but the "welcome back" toast is higher up.

Sorry if I am giving too much info, I am trying to describe the issue as best I can.

 

As an update, and maybe this helps. Magisk updated to v.12 this morning. I updated it, and rebooted. Now when I try to setup Join, I still get past the ask for my gmail account, I now get the "deny or allow" screen for Google, asking for access to Drive, and contacts access, I select "Allow" and then get a brief "Connecting Server" window with I think "joining in" that immediately goes away and then the toast message like above.
Before today, I never got to the ask for access to Drive and Contacts. It failed with the toast after I picked my gmail account.
Is it possible that Join does not like Magisk's root? I tried to hide root from Join, and I get the same errors as above.