Rigged figure in one Blender file - when append to another Blender file, it shows Armature but cannot animate First off, I have appended a number of other rigged objects via 'Collections' to Blender files before and they worked as expected. I fact, this human figure was appended before. But, during the course of editing it in project appended into, I made a mess in a variety of ways, including not being about to unhide the armature. So deleted it and appended the figure again. Basically, I am in the same situation as before in that I see in the Outliner the armature, but cannot select it.
In the end, it was simply that the Bones box wasn't checked in the Viewport Overlay.
At least it wasn't something truly disastrous... just a simple oversight.