As many others, I had the problem with the access token refreshing when connecting the account linking with a Google API.
This is a question summing up what my problem was and the steps I took to solve it.
As many answer suggested, I added '?access_type=offline' to the Auth URI
The result was: https://accounts.google.com/o/oauth2/v2/auth?access_type=offline
This was crucial to fix the problem, after disabling the application, removing Google permissions and re-enabling it, it worked.
But only for a couple of days. It now has the same issues as I did not solve anything.
The settings did not change, I tried re-doing everything, the access token is still not passed after it expires, asking for the login.