Volumio on Raspberry Pi Report Incorrect My Music Stats

I have 3 Volumio instances - 2 on Raspberry Pi (v2.907) and 1 on Mac Mini x86 (v3.083). All instances are configured to use the same NAS CIFS share from Unraid v6.9.2

For reasons unknown, the number of artists, tracks and playtime in Sources → My Music are different between the 3 instances; the 2 Raspberry Pis have a lower number of artists, tracks and playtime, whereas the Mac Mini x86 has a higher number of artists, tracks and playtime. Using the find / wc shell commands on the NAS share, the Mac Mini x86 appears to be reporting the correct count of tracks in My Music:

$ find . -type f | grep -i \.flac$ | wc -l

Please see screenshots below:

From Raspberry Pi Instance

From Mac Mini Instance

I have tried stopping the mpd service, deleting the /var/lib/mpd/tag_cache and restarting the mpd service to force the Sources to be rescanned, but it still generates the same number of artists, tracks and playtime on the Raspberry Pis every time.

Any ideas what might be causing this? Anyone else observed a similar issue? All the tracks on my NAS CIFS share are FLAC type. Of the FLAC files on my NAS, they are primary English ASCII file names, but there are about 3000 tracks that contain non-ASCII characters (if this is a factor contributing to this issue)

$ find . -print0 | perl -n0e 'chomp; print $_, "\n" if /[[:^ascii:]]/' 2>/dev/null| grep -i \.flac$ | wc -l