Click on "End" bar in timeline, try to drag to adjust timeline, JUMPS to start

[In SL360] This is happening more and more frequently: I'll make sure I've set my objects to "Show until end", and I go to drag the timeline End to the left to cut off dead air at the end of a slide, and when I click on the "End" bar and try to drag left, my view blips over to the beginning of the timeline, without shortening it. 

Seems to happen more often when I have an audio file that is triggered by a click. Usually, the audio files shrink to fit, but could this be causing the issue? I need to be able to have an audio file play but don't want the timeline duration to be 6 minutes long if my audio is. And it only does this sometimes. Can't correlate a cause yet.

Anyone else have this issue? Thanks and have a super day!