Hi,
Thank you for all the details!
From the video it looks like as some styles are either not refreshed or they might be overwritten by a 3rd party stylehseet. First, I recommend clearing all layers of cache, including browser, page, CDN, minify etc.. That alone may resolve the problem.
If not, then it is very likely a CSS override, and that can be very hard to track down. For that I will have to be able to take a look at the issue directly.