When customizing ganger colors and patterns, textures are lost resulting in a neon pink result.
It seems to occur most frequently when changing the texture patterns. Attached are my save and logs.
If you revert the melee ganger back to gang defaults and save, everything seems to be OK. Customization can continue fairly normally. But when you then select the pattern with the more vertical stipes instead of the angled stripes, and then back out of the customization window, this happens. The issue occurs when customizing patterns on either upper or lower body gear. This is consistent for me with this ganger on this save.