Problem with adept portrait, and some new portairts in general is that they use lens flares, which m3addon couldn't handle due to errors in m3 parsing - there was some most likely totally incorrect string reference to sourceFilePath. Perhaps it was a thing in older models? Though, I don't know what could this file represent, because the only external sources m3 specifies are textures.
Besides mentioned fix it also includes 2 others to stuctures.xml, that relate to import issues of some new models.
I had some plans to attempt to work on this more and get the plugin into better shape, but sadly I can't find time for this. So all I can do is simple fixes - that is when models cannot be imported at all, or are imported significantly incorrectly. Such issues are often relatively easy to track down.
Export related issues are much harder.. ideally plugin should be updated to export models in newest m3 version format, so that it can support some of the fancy stuff like lens flares, reflection materials etc. Sadly, that requires considerable research on my side.. but maybe someday.
Anyway, if you encounter some import related issues let me know - I'll see what I can do. I'd like to keep this plugin alive.
(I rarely log into sc2mapster.com these day, but I hang out in its Discord channel - easiest way to reach me.. filling bug report in github - issues tab; works as well).