In a project Portfolio, click the caret>Export>Google Sheets generates the error below (I updated the token today). Another user at my organization follows the same steps and is not having this problem. I saw the prior post for Forms, but the Solution doesn’t fix this issue.
Taking a stab at this, but I have no basis for this suggestion, so take it with a grain of salt.
Might there be a permissions issue you have to adjust on the Google end? Maybe go in and see what is authorized? Best of luck.