Gain envelope bug -- playback volume changes randomly

In X1 I have a clip with a gain envelope that sounds differently each time I play it back.  It's a pretty simple scenario...

I have a track with two lanes.  There are clips in one lane where the clip end slightly overlaps the start of a clip in the next lane.  Both clips have gain envelopes.  Nothing else is going on -- no track FX, no other automation.

When I play back the track repeatedly at the point where the two tracks overlap I can hear that the second clip's envelopes are not taking effect sometimes.  What I have noticed is that if I stop and restart without changing the "Now" playback position, the envelope effect (or lack thereof) is the same.  But if I move the "now" marker then the envelope effect changes -- even though I did nothing edit-wise.

This is pretty disconcerting because I was changing the envelope to adjust to what my ears were hearing, and couldn't understand why such minor movements made the biggest of changes.  It was only when I stopped changing the envelope and began simply replaying what I was hearing when I noticed that Sonar X1 itself is 'randomly' changing the sound level.

This makes gain envelopes entirely unusable.