As PhotoStructure synchronizes your library, it’s critical that the library database stays in synchronization with the previews directory.
If PhotoStructure crashes or is not shut down gracefully, the database may not be closed properly, and lose recently added data.
PhotoStructure keeps metadata in the previews directory to make sure that, even in this case, it can try to recover from these issues, but sometimes the recovery process doesn’t detect that there’s an issue, so previously-generated preview images are incorrectly re-used.
This should be fixed by running “re-sync this asset” from the asset view:
If you’ve found that this is a common occurrence, please reply to this topic and I’ll look into it: this (ideally) should never happen.