This bug is effecting many of the pages in the XUI. Recent changes in the UI have considerably speeded up the initialisation time of the UI which has resulted in this lurking problem becoming more prominent. We have 5 smoke test failures in 6.5.x. I cant find any failing tests related to the bug in master, however the code needs fixing here too.
The problem is that the partials are not being loaded before the routes initialise. We have an await/async function that is supposed to prevent this, but it is not working in production. It seems to work ok in development.