Reproducable at:
beta cluster metawiki: https://meta.wikimedia.beta.wmflabs.org/wiki/Special:Watchlist
production testwiki: https://test.wikipedia.org/wiki/Special:Watchlist
Not reproducible at: patchdemo with GlobalWatchlist master and no other extensions enabled, with MediaWiki:Sidebar copied from testwiki - https://patchdemo.wmflabs.org/wikis/1ec5b0d5b04520a39832bb3dc4a0533f/w/index.php/Special:Watchlist
Is there another extension or configuration option that is messing with this?