Could you share the file .obj that fails to import, preferably together with accompanying .mtl and .jpg?
Shapespark does not have any functions for cleaning up geometry data that comes from 3D scans, you would need to do it in some external program before importing to Shapespark. In general such cleanup is a difficult problem, I’m not aware of any tool that does it well.
Last time we checked, 3D data from Matterport did not separate real world objects, for example chairs could be merged together with floors, also geometry hidden from the scanning camera had holes. The textures in scanned models are already captured with light, so is doesn’t make much sense to try to bake such model.