Unable to add any Gmail Accounts to Mail

This is my first post to the community, so I hope choosing to post into macOS Sierra is the correct place to be.

Anyways. I am currently having issues with trying to add mail accounts back onto the Mail app on my MacBook. I was having issues with the accounts constantly going offline, so I disconnected them and was going to add them back to see if it would fix the issue. Well I can't add them back.

What occurs is if I go into Internet Accounts or I just add an account straight from the Mail app, I click on Google, and I put in my credentials of either account, I have two accounts in total, and then it just hangs on a gray screen and the only option I have is cancel. Hitting it just closes the window and attempting to do it again results in the same issue.

I read on a couple other forums either on here or Google forums of the same question, but the answer was always to go into Keychain Access and delete anything associated with Google. I did so and the problem still persists. I of course tried restarting and also updated my MacBook.

Now I'm not sure if this would have occurred if I wasn't on the PB, but I will say the issue with not connecting to one of my mail accounts properly, which is how I got into this as mentioned previously, did occur on the latest version of 10.12.3 which wasn't PB. It was released to everyone. So this could be a PB issue, but it's happened on two PB now and I didn't know if there was anything else anyone could suggest since this has happened to others as well that I assume weren't on PB. I also attached an image of what occurs. So anything would help.

I apologize if this is in the wrong area of the communities. Again, it's my first post. But thank you in advance.