for a while I would have an intermittent issue with importing that near had me tearing my hair out!
I thought I’d recount my experience here just to save others the grief…
first of all I’m not sure if this is platform specific I’m using Linux so other platforms may or might not exhibit this behavior
If you import a .blend file from outside your projects folder everything works just fine as you’d expect.
however if you have your .blend files in say a folder called resources at the same level as assets, src etc then the importer will fail without any clue as to why not even an exception… how many times I fiddled with my .blend without avail (without feedback how was I to know the .blend was ok?!)
the importer will kind of work if you put a folder inside the assets folder, but then it will likely have a path you don’t want, any attempt to change the path on the last stage, will also cause a failure, but half way through leaving and extra .blend file and no .j3o
So to reiterate its probably best to have all your .blend files elsewhere…