As shown in the image below, whenever you wear the mekanism mekasuit, it would render the character on top in some parts, particularly the head and the lower arms. I've encountered this issue previously but i had no idea it was palladium doing it, i only realized it when i opened the accessories tab.

Using
FML 47.2.0
Palladium 4.1.1
Mekanism 10.4.6.20 and addons, all up to date.

I assume the player model is usually hidden when you wear that suit?

Yes, it's not visible at all usually.

I'm also experiencing this issue.
Hopefully it gets fixed soon.