My Outlook (@hotmail.com) email isn't syncing after app restart

Problem

My @hotmail.com email won’t sync, and I have to re-sign into it every single time I open Mailspring.

Context

Adding a hotmail account (possible any Outlook address?), then restarting the app/computer. The account says it cannot sync. I have to sign back in each and every time.

Email Provider

Outlook (@hotmail.com)

Setup

  • OS and Version: Windows 10 Home - Version 21H1 (19043.1023)
    • Installation Method: MailspringSetup.exe
  • Mailspring Version: 1.9.1-30ef802f

I saw something somewhere that said it had to do with Microsoft not allowing the sign-in, and that I could allow it through their account activity page. I went there, but saw no such option. It would either tell me if the sign-in was successful or not.

I have the same issue, with an organizational Outlook 365 account.
To be fair, the outlook web app signs me out after a few hours as well.
However, this is exactly why I want to use a desktop client.
I have had to go back to using the web app, because signing back in to Outlook.com (including 2FA, perhaps that is an obstacle?) is still easier than doing the whole Mailspring “reconnecting” process… and because Mailspring usually takes a while to realize that it hasn’t been syncing, so I don’t know if I’ve been missing notifications until I check on it.

UPDATE: So something I find strange… is this only happens on Windows. On Linux (Pop!_OS 21.04) it authenticates just fine, every single time. Another thing I’ve noticed recently on Windows… is now my Yahoo won’t stay signed-in after restarting. And this is of course using the generated password that Yahoo makes you use for 3rd-party apps. Why is everything fine on Linux but not on Windows?