Windows 10, 980Ti, 6700k
Broken: 2.79, release version
Short description of error
Particle children are suddenly loosing their randomness. Pictures will say much more:
Left and right is the same project, but in different stadiums.
Left is old save, right is current.
Please note, all particle settings are exacly the same.
As you can see left one is cool, random. Right one has a pattern, no randomness. They are just slightly moved.
Changing segments on the left project from 5 to 4: still looks OK.
Changed segments back to 5 from 4 (original value). Suddenly: no randomness!
I can change those segments again and again and the randomness will not come back.
However (!) undo option does fix that!
But after two changes it will get broken again.
Exact steps for others to reproduce the error
I can't attach my .blend file due to copyrights, unfortunately.
I also don't know how many steps it takes to screw it up. But something is bad. I can't leave render overnight due to this problem. :(
Side note: changing the seed does not help, they are moved in different positions but the pattern is still clearly visible.