I had a folder in my NAS Library with a set of FLAC files. The Album appeared in the Windows App,

with track names corresponding to the FLAC filenames. I then  deleted the folder, and updated the Library; the Albun disappeared. I then restored the folder with copies of the files, after I had changed the sample rates and modified the filenames, which had been long anc complicated. BUT when I updated the Library, the Album reappeared with the original filenames. The files themselves are the modified ones, with the altered filenames, but the track names shown in the App are the original ones. How and why does the app remember the original names, when I have deleted the files are replaced them with different filenames ? Does SONOS just get the tracknames from a web server ?