I have started to use the comp editing techniques desribed in the videos and find the behavior inconsistent.  I drag the comping tool over the desired portion of the take and the clip is split out appropriately.  When I hit Sft spacebar, the lip starts to loop.  However, when I het the down arrow, the next clip is lelected but is still muted, i.e., the loop plays back the top comp, not the second.  I have to use the mouse to click in the second comp to make it active and use that method to change the selected clip rather than up/down arrows.  Then, when I have the best take selected and hit Sht Enter - nothing happens.  That action is supposed to elevate the selected clip to the top, but nothing happens.  Is my editor broken or am I doing something wrong?

I'm not in front of my DAW right now, but IIRC, as you switch clips using the cursor keys the highlighted clip will be heard, but it won't be visibly unmuted, The promotion and visible unmuting doesn't happen until you hit Enter (not Shift+Enter which might be part of the problem). If two clips are very similar, you might not easily hear the difference.
 
Also when you say "That action is supposed to elevate the selected clip to the top, but nothing happens.", I'm not sure what you're expecting. Promotion doesn't physically move the clip, it just makes it the audible clip in that time range. Flatten Comp is what combines all promoted clips together in a new top lane.

Thanks!!
 

brundlefly
Flatten Comp is what combines all promoted clips together in a new top lane.

 
And one day you notice that the comp lane has automatically moved to the bottom. I believe this is a bug (can't find steps to repro yet...)