Steps to replicate the issue (include links if applicable):

• Write a new English Wikipedia article clicking preview every now and then without publishing
• Quit the Firefox browser for whatever reason (it asks whether you want to leave the page you're editing before closing)
• After Firefox is not a running process, restart Firefox and restore the session where it opens the new article page that was open when closing Firefox

What happens?:
And old version of the article text is restored. Once, no text was restored.

It did not ask whether to restore the text via Edit Recovery so this may be Firefox text recovery functionality restoring the text and it's possible that this recovery is interfering with the Wikimedia text recovery. I could only restore the text because I made sure to paste the article content into my notes before quitting Firefox.

What should have happened instead?:
It should restore the latest text.

Software version (on Special:Version page; skip for WMF-hosted wikis like Wikipedia):

Other information (browser name/version, screenshots, etc.):
Firefox

Edit Recovery usually works fine and does ask whether to restore text but for the Wikipedia article creation text box (where this is most useful) it didn't work and this happened multiple times as I had to close the browser multiple times in between. Probably quite a few users lose some changes, having to redo their work.