Hmm, this is interesting- I'm not using forestset from layers, I'm using them as direct object references. Here is my workflow-
1. Raw geometry assets are saved per file on our drive (in a separate folder than the FP library thumbnails and xml files). ForestSet objects are saved in each assets file as well, and the assets are directly added to the forestset object.
2. in the library, everything is imported with import objects from 3ds max files, and the forestset objects are selected. then if i load this forestset into an FP object, everything seems to work just fine.
3. I add another folder in the library for preset forestpack setups, and try and use the forestset objects from the library to populate these. The forestpack object works just fine in the scene, but once i save it to the library and try and reload, it only loads the forestset object and doesnt get the embedded objects inside of it: "warning: can't find object in the source scene". I thought this was due to the unique layer renaming but when i turned that off it just hard crashed instead on loading.
Thanks and I hope that explains a bit better!