Objects greyed out

Just transferred route to another hard drive and now find many trees are either greyed out or blocky. Also, although you can grab them in surveyor, they are not in the surveyor list, so cannot use replace assets. Tried edit and came up with; "The file "trees.lm" is provided in LM format despite containing only single mesh.

All double dutch to me, anything I can do?

Thanks in advance,

Ed.