Hello @lowfreq84,
Thank you for contacting us.
Please consider that the OBJ file protocol is not a Corona feature. This file-type is an old file exchange protocol which supports native materials from the host app.
This means you can only migrate standard/basic materials and/or shaders/maps from one host app to another. If you're trying to migrate assets using specific materials/maps from a specific render engine to a new host app, then this is not supported by this file-type, or at least, geometry should be imported ok but materials will requiere additional work.
I hope this helps.
Looking forward to hearing from you.