I've had trouble accessing the Google Analytics dashboard(s) in FF as well. Nothing gets rendered except the background gradient.
In the interest of not using Chrome though, when I run into such issues I use Brave as it's Chromium-based and thus allows me to side-step those problems.
The times I had problems with GA was because of some uBlock rule or weird A/B tests (I assume) or caching, clearing cookies and site data fixed the problem.
