Ctrl+Shift+R convinced Firefox to load the home page properly, but no luck with Chromium despite seeking how to do a full reload of a page.
One thing I don't understand though is that say Chromium on my PC or Firefox on my phone had not been used to visit the site before and yet still received a blank page. Nor does the official advice for hard-reloading a page in Firefox for Android make any difference.
- edit - out of curiosity I tried Ctrl+Shift+R on a spare FF profile that hasn't viewed the AT forum site before, before and after the hard reload it still gave a blank page. I have no idea what's going on here.