I updated all translations from the mainWP Dashboard (overview) page, which updated them for 2 sites. After that I started a Sync All, which was executed fine, but it showed the output of the previously executed translation updates in the modal. So the upper half is correct, the bottom half isn’t.
This error was in the browser console, but I’m not totally certain if it’s related to this issue:
Uncaught (in promise) Error: A listener indicated an asynchronous response by returning true, but the message channel closed before a response was received
I can’t reproduce this issue on MainWP 5.1 RC2 — neither the console error nor the modal information.
Do you remember if the browser page refreshed automatically after the translations were updated, and were there any update errors with the translations?