When I try to add an additional Gmail IMAP acct to TB, TB finds the configuration in Mozilla ISP database. When I click the Done button below, an accounts.google popup windows opens saying "Sign in with your Google Account". The account email address is correctly shown in the box below, but when I click Next (to progress to the password screen), the box is cleared. So, I can never get to the password screen because it seems Google doesn't recognize the account. It's so weird. Any ideas/suggestions gratefully received. Background info: - This account is valid and signed in/working in on multiple other devices - The account has Google 2SV (2-step verification) activated - The email address and password have been correctly entered - I'm running latest version of TB on Win 10 PC. - I have 4 other Gmail accts syncing email to TB just fine under IMAP. The URL for the accounts.google popup window is below: https://accounts.google.com/ServiceLogin?continue=https%3A%2F%2Faccounts.google.com%2Fsignin%2Foauth%2Flegacy%2Fconsent%3Fauthuser%3Dunknown%26part%3DAJi8hAM6O3TMwzkjKUbevk8YjZISn2cEipi5oWbPdJTSVEzB5fzDCau-UhovwcSkRdHkUqjNqkJqG3lp1y0hOLfNf8f4l0Yo1b41FvevixqfZGoAsXEOFWlCls9-GiCVItS5RI3A3embh7jpQAoceU1-ybmhkOHsE4a9Cwp0BQXkKpKnJHzQfALpdIkNXs1wlXC5p6UpC3IQp-VhYURdm--txgd_3zWbnXH2PpQYIxE_2oMBZk4yS_eJvcXrBGGRre2qOqUwgicqVXQ5i86MkJ4IDc1fc6LfoPTdaFlp1GGnhbb-p4FLd8BdHqOqs-PcPQ-x-VF6G9yrts97yxYsUM20UIjmds4oy6Xc7BEyTwjEg5O6IXGSMLixrAwUuxt3kli1e9slepWMLZv72xZgBM63lMPmRRISJixCi8QfyaLnZGyxc7tZdMZMqOcIOSN4fPZbJwToiZuOLbOD9IVUamGsJQd4jxE33w%26as%3DS-1525975062%253A1667071197737182%26client_id%3D406964657835-aq8lmia8j95dhl1a2bvharmfk3t1hgqj.apps.googleusercontent.com%23&sacu=1&passive=1209600&oauth=1&Email=jfh.trash%40gmail.com