EVer since updating to 5.5, I have been having this issue. Since updating, the main issue I was having with groom, mainly the hair exploding during animation, is mostly fixed, but now I have run into another issue during animation. Groom assets imported via 5.5 become jagged and essentially, low poly, to the point of looking like tiny blades that allow you to see directly to the scalp. (images Provided)
During Animation:
This one is when the Metahuman is static, prior to animation:
I would like to believe this is a render issue and not an internal software issue, but im not sure. If anyone has any insight, please send it my way. Im at the tail-end of a project that this is literally the LAST PART before I can render this out.
For Better reference, here is the image of what it looks like in the Groom Asset Panel:
