Why don’t my connected Gmail accounts show? I tried adding, and doing the verification, but they never show in my app.
The most common cause of this is that port 12141 on your local machine is being blocked. Mailspring uses a small local webserver on that port to receive the OAuth callback from Google — if a firewall, VPN, or security tool is blocking it, the login flow completes in the browser but the account never gets added to the app. Try temporarily disabling any VPN or firewall and attempting the login again. If that doesn’t work, you can add the account manually using IMAP/SMTP with a Gmail App Password instead.