We are tracking an issue with Act! Connect Link (G2C) where the token fails to authenticate. Desktop users that have Act! Connect Link installed for AMA access are experiencing a JWT Token error. Other apps (including Act! Companion) that use the Act! Connect Link URL will also fail to authenticate.
At this stage the only known solution is to uninstall and reinstall the Act! Connect Link, which generates a new URL.
Once you have the new URL you will need to update any other app with your new URL