Manual testing shows that the UMA AccessEntryPoint enum value fluctuates depending on whether Chrome is running or not. In either case, it seems we're sometimes getting the wrong value.

When tapping links to offline pages from a CCT error page, I was able to get CCT as well as Net error page.
When tapping links on a Chrome error page, I seem to get CCT!
I also saw some reports of 'Reloading page' and 'Clicking link'. Reloading page was actually due to reloading a page. I'm not sure the source of the 'Clicking link' report.