Group Members + Raid Frame not updating at group change?

[gdujj]

Basically, when I join groups with someone, I can see only myself, as when I am alone. As if the trigger to suddenly make that other players' unit visible isn't being fired.

It's the same if I join a raid group.

Initinally upon joining a group and seeing that the group/raid frames don't update to show the additional members, I thought I've missed some sort of "initilisation" command.

But I can't see anything like an init command on other group/raid mods, nor on the default. And I find it hard to understand how I missed this aspect since I based my HP plates on another (fully working) mod.

Can anyone see what I'm missing in the XML files? Is there an instruction to, say, "reassess group size, if changed, re-render group area"? ... "hey a new member has joined, make his HP frame visible", that sort of thing