meshes not showing

[tegleg]

hello (btw i have bought this asset)

with obi 5 i can rarely get a mesh to show.
following the video tutorial normal meshes like the built in shapes, cube, sphere, work fine, however
just about any other mesh does not show.

when i am creating the blueprint the particles, constraints and mesh show fine. but when i put them in a level, assigning the blueprint to a soft body asset, nothing shows up.
the object falls with gravity etc but the mesh is 'invisible'

any ideas whet this could be?
unity 2019.2.14f1

thanks

edit:
here is one i tried just to test
https://free3d.com/3d-model/cat-65064.html