On Chrome, MacOS High Sierra, I see the following the JS console:
Uncaught Error: No infusion data found: undefined at Object.OO.ui.Element.static.unsafeInfuse (load.php?debug=false&lang=en&modules=oojs-ui-core%2Coojs-ui-widgets&skin=vector&version=0us3uht:8) at Object.OO.ui.Element.static.infuse (load.php?debug=false&lang=en&modules=oojs-ui-core%2Coojs-ui-widgets&skin=vector&version=0us3uht:7) at Object.OO.ui.infuse (load.php?debug=false&lang=en&modules=oojs-ui-core%2Coojs-ui-widgets&skin=vector&version=0us3uht:3) at HTMLTextAreaElement.<anonymous> (<anonymous>:78:16) at Function.each (load.php?debug=false&lang=en&modules=jquery%2Cmediawiki|mediawiki.legacy.wikibits&only=scripts&skin=vector&version=1nv7gwr:4) at jQuery.fn.init.each (load.php?debug=false&lang=en&modules=jquery%2Cmediawiki|mediawiki.legacy.wikibits&only=scripts&skin=vector&version=1nv7gwr:2) at HTMLInputElement.onChangeGlobalCheckboxes (<anonymous>:77:8912) at HTMLInputElement.dispatch (load.php?debug=false&lang=en&modules=jquery%2Cmediawiki|mediawiki.legacy.wikibits&only=scripts&skin=vector&version=1nv7gwr:69) at HTMLInputElement.elemData.handle (load.php?debug=false&lang=en&modules=jquery%2Cmediawiki|mediawiki.legacy.wikibits&only=scripts&skin=vector&version=1nv7gwr:66) at Object.trigger (load.php?debug=false&lang=en&modules=jquery%2Cmediawiki|mediawiki.legacy.wikibits&only=scripts&skin=vector&version=1nv7gwr:112) at HTMLInputElement.<anonymous> (load.php?debug=false&lang=en&modules=jquery%2Cmediawiki|mediawiki.legacy.wikibits&only=scripts&skin=vector&version=1nv7gwr:113) at Function.each (load.php?debug=false&lang=en&modules=jquery%2Cmediawiki|mediawiki.legacy.wikibits&only=scripts&skin=vector&version=1nv7gwr:4) at jQuery.fn.init.each (load.php?debug=false&lang=en&modules=jquery%2Cmediawiki|mediawiki.legacy.wikibits&only=scripts&skin=vector&version=1nv7gwr:2) at jQuery.fn.init.trigger (load.php?debug=false&lang=en&modules=jquery%2Cmediawiki|mediawiki.legacy.wikibits&only=scripts&skin=vector&version=1nv7gwr:113) at jQuery.fn.init.jQuery.fn.(anonymous function) [as change] (https://test.wikipedia.org/w/load.php?debug=false&lang=en&modules=jquery%2Cmediawiki%7Cmediawiki.legacy.wikibits&only=scripts&skin=vector&version=1nv7gwr:113:763) at HTMLDocument.<anonymous> (<anonymous>:79:327) at mightThrow (load.php?debug=false&lang=en&modules=jquery%2Cmediawiki|mediawiki.legacy.wikibits&only=scripts&skin=vector&version=1nv7gwr:49) at process (load.php?debug=false&lang=en&modules=jquery%2Cmediawiki|mediawiki.legacy.wikibits&only=scripts&skin=vector&version=1nv7gwr:50)
The form looks OK, and appears to be usable, and the JS for "Select options below to be global" still works, etc., but changes to my preferences don't save.
After saving a preference in Firefox, however, I'm able to come back to Chrome and everything works as expected (but I still see the above JS error in the console). If in Firefox I uncheck "Select options below to be global" for all tabs, save, then go back to Chrome, again changes to preferences don't save.