You may have found a bug. Can you provide more information about the cue you are stopping?
What does it's content look like?
Is it an interactive cue (IsInteractive = True)?
Do you have sound variations?
Do you have a release RPC on the sound?
How many tracks on the playing sound, and what do they look like?
Are there wave variations on the Play Wave event(s)?
Is there a release waveform (is there a loop region within the playing wave that doesn't extend to the end of the wave)?
If the wave is looping, is the "PlayRelease" flag set?
The more info you can provide, the quicker (and easier) we can troubleshoot the problem.
Thanks.