Modulation vector not used when play position is selected manually

Software Version: Synfire 1.8.5 build 5
OS: Windows 10
Bug: Functionality misbehaviour
Reproduce-ability: 100%
Reproduction steps

1. Start new Arrangement
2. Draw a figure
3. Draw modulation information corresponding to the figure
4. Select 2 bars of duration for playback
5. Play back (modulation is used correctly)
6. Select last bar of duration
7. Set the playback cursor to the beginning of the first bar
8. play back (modulation is not used within first bar, but used in the second bar where the selection starts)