Having recent issues with this too, used to work fine.
Having just revalidated the token in run mode (debug_mode=true), the token seems to stay valid for only a few minutes before the error shows up again.
This is despite Linkedin dev portal showing that the access token is still valid.
The weird thing is that users still can authenticate successfully and even retreive emails via https://api.linkedin.com/v2/emailAddress?q=members&projection=(elements*(handle~))
The error seems to only impact getting the profile details (https://api.linkedin.com/v2/me)
Any help would be much appreciated!