Hi everyone, hopefully I can explain this clearly.
On one of my projects this past week, parts of my drum kit are not playing back.
The notes are there, there's just a pause, and it actually makes it seem like
the song is stopping momentarily, even though all the other tracks are playing normally.
It's not every measure---it's about every four and just the first few beats--so it's the HH and Kick.
As background: I am using Sonar Professional. But the track was originally recorded with
Sonar X1 LE, so it was the old basic drum kit.
I thought that might be the problem somehow, so I muted the track and inserted a pattern
from Addictive Drums in a different track altogether, and the problem was still there.
Anyone have any idea what might be happening here?
 
 
edit: added [Solved] to the subject - sc

Dropped MIDI notes are usually an indication the "Prepare Using nnn Millisecond Buffers" value in Preferences > MIDI > Playback and Recording is too small. The default is 250, try 500 or 750.

Thanks for the fast answer; that was it!
Amazing, I really had no idea.
Two and a half years of this and a lot to learn still, apparently.

You are welcome.
I will update your initial post as solved.