[nextos]

Maybe you ran into their daily IMAP usage cap?

[lilactown]

That's a reasonable hypothesis. My experience was mbsync would hang for many minutes, and eventually when I revisited the terminal it was in it had failed with a nondescript error.

[guiraldelli]

You are definitely running in the GMail's IMAP daily limitation [1].

It took me three days to fully synchronise wuth GMail, but ince done, it takes milliseconds, now.

[1]: https://support.google.com/a/answer/1071518?hl=en