Multisite Subsite Issue

Been using Super Cache on this mulitsite for a couple of years now with now problems, out of the blue the subsite about couldn’t find ita images and style sheets. Deactivating the plugin for this website corrected this, though I’m left with some minor styling issues. I cannot now access the theme cutomiser to correct the styling issues with Super Cache deactivated.

My main site and other subsite are not having this problem with super cache.
Please can you advise?

The page I need help with: [log in to see the link]