Steps to reproduce:

1. Login to any Wikipedia, add some pages to the watchlist and edit some of them (e.g. sandbox)
2. Check "Hide my edits from the watchlist" in Preferences (tab Watchlist) and save
3. Open Special:Watchlist
4. Uncheck "my edits" and click to the "Show" button

Expected behavior:
My edits should be shown. Yesterday it worked across Wikipedias

Current behavior:
My edits are still hidden and the checkbox is checked back somehow magically