I may be experiencing a similar issue. However, my circumstances, are likely, entirely different. I have just had all my data recovered, from a damaged external hard-drive, and placed on a new harddrive. Many of my files were recovered and they were put in a folder named: “Long path files”.
This “Long path files” file contains thousands and thousands of small data files. My theory is that this has broken-apart/scattered, the once upon a time, Audacity “_data” folders into thousands of files. It appears that the “_data” files have broken into thousands of “AU Format Sound” files. Could this be? Are these what are considered broken pieces of data folders?
Lastly, I should mention that all of my recovered “AUP3” Files are functioning properly when I open them up with the latest Audacity version. Sadly, all of my “Audacity Project Files”, which used to be called AUP files (before the data recovery), are not working at all. Furthermore, when I open these Audacity Project Files, I am met with error messages, in the Audacity Program, that read: "Couldn’t find the project data folder: “Example_data”. Then another error message: “Could not load file: ‘E:\HardDrive\Long path files\Example.aup’”.
Any information about AUP Projects files and their pieces would be greatly appreciated.