Created attachment 8881894 [details] CustomizeTabSometimesFailsToLoad.png In Nightly 56.0a1 I see an empty Customize Tab spawn when I click the Customize option in the Hamburger Menu. Upon several retries it will load. But repeating the flow I will again see the issue on a different session. Also, in some attempts the Customize button doesn't prompt any response at all in Nightly.
Cannot replicate on a new profile.