Some head morphs are actually combinations of several different morphs.

For example "eye-depth" will reshape the head mesh around the eyes but also automatically move the eyeballs along the z-axis.

If you combine that morph with others into a new morph, the auto-link to the eyeball movement gets lost.

Solution: Move and/or scale the eyeballs manually until they match the new headshape again, or create a new auto-link using the dependency editor.