Why does scanning music library take longer on windows as oppose to my synology?

I believe this started two updates ago. Two of my music libraries scan extremely slow. You do not even see the scanning files indicator on the bottom anymore. I can scan the same library on my NAS and it scans super fast like always. Is this a known issue?

I’ve got the same problem on Plex Cloud with Dropbox. The movies and TV shows will indicate items scanned but the music won’t show anything and takes days to fully scan. Not to mention the music scan won’t remove items I’ve deleted from my cloud storage. A Plex employee says they’re looking into it.