I have a fresh install of Magento 2.1.5 and everything is working great except for one massive thing. The side menu in the admin panel only works with IE or Microsoft Edge. When using Chrome or firefox the links don't respond and the menu does not expand at all. I've cleared my cache on both ends and even completely reinstalled firefox since I don't use it much anyway but it still doesn't work.
I can temporarily fix it by clearing everything except .htaccess in pub/static, but after one session the menus stop responding again.