I could use some help troubleshooting this. Here is my site. None of the drop downs work, for example when using fixedhead.xml clicking the icon for "Account" should show a menu, but does nothing. Everything was fine in 1.27.
Topic on Skin talk:Chameleon
It's a known (and fixed) problem. Try using the dev-master version (or wait for a release).
Thank you. Updating using composer require mediawiki/chameleon-skin "1.x-dev" fixed the problem.