As the title says, hairstyles are not keeping painted rigidity if you edit the scalp mask at all.
Can be easily recreated:
1.) Create and save a hairstyle with painted rigidity (or use an existing one).
2.) Edit scalp mask and click 'Finish'.
I know there is a warning about losing style for the settings included with changing the scalp texture, but they do not clearly specify the mask is also affected.
If it does in fact apply to the scalp mask changes intentionally then the notice may need to be made more prominently encompassing.
My impression however is that this is not intentional, but a bug, not a UI issue.
Can be easily recreated:
1.) Create and save a hairstyle with painted rigidity (or use an existing one).
2.) Edit scalp mask and click 'Finish'.
I know there is a warning about losing style for the settings included with changing the scalp texture, but they do not clearly specify the mask is also affected.
If it does in fact apply to the scalp mask changes intentionally then the notice may need to be made more prominently encompassing.
My impression however is that this is not intentional, but a bug, not a UI issue.