So you mention you packaged and it worked roughly three weeks ago. If that is the case, it could be lingering references from previous iterations.
Try deleting your Saved and Intermediate folders to see if that resolves the issues. Also be sure you make a copy of these folders before deleting them.
I would also look into re-importing the assets in question and then re-saving your project to see if that helps. Aside from that, this seems to be a project specific issue. Unless I can get some repro steps and can repeat this issue in a blank project, it is going to be hard to figure out what is actually happening.
Thanks,