Hi guys! so i have a question, back in the 2016 days i remember i had no issue assigning hair bones, but nowadays, for some reason, all hair bones EXCEPT "c_hair" keep coiling up on itself. does anyone know why this happens? in this picture, the bottom portion on the back of the sim the hair is assigned to "b_hair" and in the front, the bottom portion is assigned to "f_hair" but as you can see it just coils up in on itself

Most likely it's either
1: Bone weights don't add up to 100%
2: is also assigned to a bone it shouldn't be assigned to
3: Long hair that goes past the shoulders usually need to be assigned to other bones, most likely Spine 2 and/or 1 depending on length. The hair bones mostly affect the top/sides of the hair. The hair bones are at the top of the head, so they have a limited reach. From the shoulders down, the body joints usually need to take over most of/all of the hair animation, especially if the mesh is close to the body (a loose ponytail would be slightly different). If the lowest parts of the hair are just assigned to the hair bones, you'll get some weird issues.

Are you using Milkshape or Blender?

1 and 2 are defo not the reason. about number 3, yeah im well aware about spine 2 and all, im pretty good at making smooth movement, but still it coils up on itself and its not just the length, because in short bobs or even around the center (neck area of a long hair mesh) i can still animate it fine with c_hair (in the picture above, most of the hair around the neck is assigned to c_hair). also using c_hair on the lower ends of long hair doesnt give an issue, so im 100% sure its exclusively a b/f/l/r/ bone issue. im using milkshape, i wonder if it has anything to do with that.. some update between here and 2016 maybe...

Have you checked the individual vertices in the "broken" parts?

Depending on how you assign the hair (manually or via auto tools), the auto tools can sometimes add in bones they're not supposed to.

One thing I often do is to check the animation in Milkshape by activating the ANIM mode (make sure to save the file first, as this approach can cause some borkage), and then rotate the joints to see if each mesh part is behaving properly. If anything is misbehaving it's much easier to fix it in Milkshape first, instead of going in and out of the game (you need to reopen the file, or have two open windows - one for the workfile and one to check animations using a copy of the file)