Steps to reproduce:
- Go to Spezial:Preferences#mw-prefsection-watchlist and enable a filter, e.g. check "Hide minor edits from the watchlist"
- Go to Special:Watchlist, note that the filter is checked by default as expected.
- Uncheck the filter (and, depending on your settings, click the "Show" button to apply the change).
Expected: The filter is (temporarily) unchecked, overriding your preferences.
Actual: The filter is checked, always enforcing the settings you made in your preferences.