Steps to reproduce:
1.Open attached ’ParticleSystemMultiplier.zip' Unity project
2.Select ‘Particle System’ object in Hierarchy
3.Check ‘Start Speed’ and ‘Start Size’ values in the Inspector
4.Enter Play mode
5.Check ‘Start Speed’ and ‘Start Size’ values again

Expected results:
Minimum and Maximum values of ‘Start Speed’ and ‘Start Size’ are changed after entering Play mode
Actual results:
Only the Maximum value of ‘Start Speed’ and ‘Start Size’ is changed after entering Play mode

Reproduced in: 2017.3.0a7, 2017.2.0b11, 2017.1.1p2, 5.6.3p3, 5.6.2p3, 5.6.1f1, 5.6.0p4
Didn’t reproduce in: 5.6.0p3, 5.6.0p1, 5.6.0f1, 5.6.0a3, 5.5.4p5
Regression introduced in: 5.6.0p4
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Multiplier is only supposed to change the max value.
To set Random Between Two Constants values, both min and max values have to be entered, e.g.:
main.startSize = new ParticleSystem.MinMaxCurve(minVal, maxVal);