Example way to reproduce (but may also be one of the problems under bug 46716):
- Open Special:LanguageStats
- Select a page with many outdated messages and go to "Outdated"
- Confirm all messages till the end of the page
Now Special:Translate will slowly apply your changes and switch the icons from "Outdated" to "Translated" (in no particular order). If you exit the page too soon, your changes are lost.
Expected: user is given "You have unsaved changes" or similar before abandoning the page if some updates are still in progress.