Why my main site Meta Slider not working

Dear Sir,

After I add My custom CSS,my main site Meta Slider not working.
I have delete what I added CSS and Meta Slider preview is still working.

Please see blogs MU child option feature setting is right or not?
or what I should do?
https://premium.wpmudev.org/forums/topic/how-to-let-registering-blog-url-dropdown-show-at-home-page#post-564101

Thanks!