Can't connect my Gmail/Google account

Every time I try to publish a Zap that uses my Gmail account, I get this error:

“Authorization Error
Error 401: invalid_client
The OAuth client was not found.”

Before getting this error, the Zap test was successful: it took an email based on a certain criteria and added a row to a Coda table with information from the email. But when I publish the Zap, I get this error and can’t proceed with Publishing the Zap. 

Any help would be very appreciated, thanks!