How to "unmute" after "isolate clip..."?

Somehow, using "isolate clip(s) in layer", notes get muted and I can't find a way to unmute them.
 
Recipe: get two layers on one track. Call them layers 'A' and 'B'. Layer 'A' overlaps and is longer than layer 'B' (starts before and ends after). Select layer 'B' and use the "isolate clip(s) in layer" operation (in the right-click menu, or w/ shortcut ctrl-1).
 
That changes the color of the events in layer 'A' that overlap layer 'B'. Those notes won't play, but they don't quite have the appearance of notes that were legitimately muted with the "mute" tool. They are a solid color (slightly different from the "muted midi clip data" color), but sometimes the color changes and blends into the background so much that they are too hard to see. Muting and unmuting layer 'A' does not restore the muted notes. The mute tool applied to the notes in PRV won't restore them either.
 
When I copied and pasted those notes, they pasted "normal", and they played. That is also different from legitimately muted notes, because when properly muted notes are copied/pasted they remain muted.
 
The "isolate clip(s) in layer" operation works differently when applied to a layer that entirely overlaps another layer (as my Layer 'A' does). In that case, the smaller clip is muted at the clip level. That muting is easily undone with the 'k' shortcut, aka "clip mute/unmute".
 
Anyone want to try?
 
Bill B.