@spiritovod
Thank you for the reply. I really appreciate the quick response
So, umodel actually works very well at viewing and exporting Unreal Marketplace assets too. I've used it quite a bit for that and it does a great job.
The only time the "Mesh has no LODs" error occurs is with certain assets that have meshes labeled with "SM_" in their name.
All other marketplace meshes and assets seem to work perfectly with umodel. I can load them up, view them, and export the meshes as glTF 2.0 with .TGA textures, for editing in Maya.