Editing a MIDI map.  Everything was working just fine.  Now when I click to add a note (using Piano Roll View) the note shows up, but does not play on playback.  The velocity is set in range.  When I click on the note it sounds, just not during playback.  If I copy a note already in the MIDI map and then paste it in where I want it, it DOES play.
 
Have I changed a setting so it's ignoring notes I'm adding?  Not sure how to fix this, it's driving me crazy trying to edit this way!
 

Have a look at the MIDI playback buffer. Try increasing it to 500 msecs.

Prefs--->MIDI-->Playback & Recording

Changed MIDI playback buffer to 500 msec.  That didn't affect it...

what are your outputs for the drum map?

Are you drawing into the correct track and channel? It's reasonably easy to start drawing data into the wrong track if the in focus track isn't the one you think it is.

Is it a drum map? I thought the map bit was a typo.

Yeah, what's a Midi map?

I reckon the note is set to the wrong Midi channel.

Click on it and edit it via the Event Inspector in the Control Bar

Somehow I get the impression that the OP calls  Piano Roll itself a MIDI Map (??)

"If I copy a note already in the MIDI Map and then paste it in where I want it, it DOES play." he writes. There are no notes to be played and pasted in a MIDI (Drum) Map, are there? 
 

Sorry for the confusing nomenclature.  I guess "map" isn't the right wording.  I've predominantly used MIDI for drum maps, and with the editing I'm doing it feels more like a map than a track to me!  This is a bass synth,the MIDI track was initially input through keyboard and I'm editing.  It goes out to the synth.  Synth then outputs to a bass instrument track.

I looked at the Event list, the offending notes show up in the track's event list, in the right place.  I don't see anything different from the other notes that ARE playing. 

I DO have 2 take lanes for this track, the first take is a muted clip and I've set the view settings in PRV so the muted clip(s) don't show.  My first thought was that I was somehow placing this note into the muted lane, but then it shouldn't be visually showing at all.  Is it possible that I'm inadvertently adding the notes into that lane so they're showing, but not into the clip?  I would think if they weren't part of the muted clip they would play, and if they were part of the muted clip in the take lane I'm not using, then they would neither show nor play.

I used this same process in a project I just finished and didn't have this problem...

I just tried un-muting the take lane I'm not using, it didn't make a difference.  Then in re-muting it, I accidentally muted the clip with the added note -- in the take lane I'm not using.  So I'm NOT putting it in the lane I thought I was; but it still doesn't explain why it's not playing.  The unusued take lane is not muted, just the clip I tracked using keyboard.  The "mini-clip" with one of the offending notes is NOT muted, but it's still not playing.

So I suppose that's a clue as to what is going on, but I'm still not sure how to fix it...

And how do I select the take lane to input into the data within that clip?  I thought that's what I was doing, but obviously not. 

Correction -- I just tried unmuting the CLIP in the take lane I'm not using...