And I don't find any way at all to see to those last 4. I don't see the issue with remlaps-lite, which only has 12 communities. So, in order to duplicate it, I guess you'd need to be a member of 23 or more communities.

Yes, I've got it now, thank you 🙂 I'd implemented a max-height on the "visible" class (which is added in a self-explanatory scenario 😉) - this overrides the default height of 0 (which hides it in the opposite scenario). So to remove the height: 0, I added height: 1000px which wasn't enough. So what I should've done, was simply use height: unset and then it will cater for as many communities as your heart desires.

New observation today, when I scroll down on someone else's "communities" page (i.e. here or here), when I get to the bottom it somewhat abruptly snaps me back to the top of the page.

It did that to me yesterday when viewing a profile with posts / comments shorter than the height of the navigation. I have a feeling this one's going to be a pain to debug.

UPDATE: I've found where the problem is. Now, I need to somehow figure out why it's doing what it's doing!