PVR won't display - ?hanging

[Charlie Heard]

Recently my PVR window has stopped showing anything except the top bar
(logo, Search, Recordings, etc) when I start it from the menu. If I
refresh it, the window again shows it's trying to load something for
several seconds, then stops with the same top bar displayed and
nothing else. The annoying thing is that it will very occasionally
display part of the results, but fails part way through. It's as
though the PC is taking too long to respond and it times out. The CLI
version runs fine, just the browser-based manager.

I'm running the latest version of Windows 10 and the Brave
(Chromium-clone) browser, but it also fails in the same way on Edge. I
even resurrected Internet Explorer, sadly with the same result. I did
wonder if Norton might have started causing issues, but I can't see
any associated messages when I start the PVR.

Any thoughts?
Charlie