I did some experiement and think this still has something to do with minimum speed. Most likely caused by the pale section in the middle which is too slow. Though I didn’t expect the FM will alter the movement in such a way that it affects the commencing downward stroke.
Here’s an example script I’ve made:
example.funscript (3.6 KB)
Pattern A
Pattern B
Pattern C
All three patterns has a downward stroke of 450 unit/s.
Pattern A has an upward stroke of 58 unit/s and is performed as-is.
Pattern B has an upward stroke of 90 unit/s followed by a stroke of 35 unit/s. These two strokes are combined into a single upward stroke, and the downward stroke is executed early at a drastically slower speed.
Pattern C, curiously, bypassed the optimisation and is performed as is.
I think what I learnt today is that vibrations can also be used to script slow movement that would otherwise performed incorrectly on the machine…