[SOLVED] Animation keys are not selectable

It's suddenly impossible to select animation keys or events in the animation view. This includes both drag-marquee selection and individual selection attempts. The triangles to the left of position and rotation work fine (i.e. expanding to reveal X, Y, & Z) but I can't select the keys on the timeline, events track or even the Add Curve button (btw, is it supposed to say "Add Properties" and not add curves?). Anyway, both the dope sheet and curves editor are misbehaving in the same way.

I checked the files via Windows Explorer and they aren't set to read only. Reboots and restarts aren't fixing it. It's behaving like it's locked, but I can't locate anything verifying that possibility. BTW, reverting the layout to factory setting didn't work either.

The following linked article says there should be an icon to lock/unlock the view, but my view doesn't have this icon (see attached image). Here's the article: https://docs.unity3d.com/Manual/animeditor-UsingAnimationEditor.html

Unity4.6.9 :: dX11 :: Win10

 

So the fix is to make sure the prefab is active in the scene. In my case it wasn't because it wasn't directly in a scene to begin with. It's in an asset folder and only being referenced by a holder/null object via a script, so it hadn't occurred to me that this would nullify the ability to alter it. Which is a little counter-intuitive since the whole point of prefabs—IMHO—is to affect changes globally from a single place. Having to drag something into a scene to alter it doesn't make much sense. No worries though, when in Rome...

The missing lock icon is most likely due to using version 4... ??