"Assign clipping mask to Mask Artmeshes have problems"

[onyx totem]

What should I do to resolve this problem?

[delicate pebble]

one of them is clipped to a layer you deleted, so you need to delete the "null" in the clipping space
the others are clipped to a layer that or is hidden or is not rigged completly in the parameter [this is for example that if you dont have a keyform on both ends of the parameter]