Thanks, everyone, for the suggestions. My apologies to Gregory posting about a different issue in this thread. I thought it was the same, from the description given.
- I've tried Chrome, Safari and Firefox in OS, all with the same results. I've tried Chrome in Windows, also same results.
- I've asked the admin in NZ (our IT guy) if he's okay with me changing the theme - waiting to hear back. I suspect not, as he spent quite a bit of time tweaking it after the upgrade.
- Connectivity is likely an issue as I'm in Malaysia and since the lockdown, the internet has been much slower. But things work perfectly in MoodleCloud, so I'm not sure why the difference.
Anyway, you've given me some ideas, so will keep trying.
Regards,
Janice