Google drive api issue ... token works with go but not using Postman

I have a token.json file from google drive api … which I know works in my go code.

The token.json file has a Bearer token. But when I put that in as a Bearer token in Postman, google gives me a 401 “Invalid Credentials” … my token has ample scope for the simple GET request I’m running. My GET has a simple url …

https://www.googleapis.com/drive/v3/files/FILE-ID

If I try to use the OAuth2 panel to get a new token … Postman gives me a "Could not complete OAuth2 login … ".

I’m using Ubuntu with Postman 7.28.0

Many thanks.
Geoff Russell