I have the same problem, even on albums with a single artist.
On some albums all tracks are picked up, and on some only the first track is visible in MM8.
This problem is so far only on a ASUS VivoTab Smart ME 400C with Windows 8
My music is mainly stored on a Netgear ReadyNAS Ultra 2.
I have one license ov MMW 4.x Gold that i run on a Alienware laptop with Windows 8.1 and it finds all tracks of all albums, i think.
I am also testing MM8 on the laptop and it seems to find all tracks, i made a test by copying some albums to a temporary folder and asking MM8 to search this folder and all tracks are visible in MM8.
When i first discovered the problems on the VivoTab was after a fresh install, testing the Wifi sync.
After that i, removed all tracks in MM8 and on disc in VivoTab, copied the same albums as i tested in MM8 on the Laptop to my music folder on the VivoTab and asking MM8 to scan the folder, same result, for some albums only the first track shows in MM8.
Then i uninstalled MM8, deleted the albums files and folders, upgraded the VivoTab to Windows 8.1, reinstalled MM8 and copied the same albums to the VivoTab and asked MM8 to scan the folder.
Same result, only the first track of some albums show in MM8.
Now its getting frustrating...
But, if i choose "Folders" in MM8, still on VivoTab, i can browse to the albums folders, see all the files and also play them.
So, the files themselves seems to be ok, MM8 is just not adding the tracks to the library, in either Wifi Sync or folder scan.
I also just installed MMA on a HTC One and tested to Wifi Sync a small playlist, including the same albums that was causing problems on the VivoTab and all tracks show in MMA.
Since the same tracks that not is showing in MM8 on the VivoTab is actually showing in MMW and MM8 on the laptop and also in MMA on the HTC it does not seem to be a problem with tags, more the combination of MM8 and a tablet (ASUS VivoTab in this case.)
I am planning to use the VivoTab in my car, for communicating with the fuel injection but also as a media center and MM8 should be perfect with its nice GUI but currently theese problems makes it impossible.
I am restoring/rebuilding a 1966 Impala and show the progress on my blog at http://www.tomme.se
that is currently ranked #2 on a top 10 list of motor blogs in Sweden and i have about 1000-1200 visitors per month from many countries.
The usage of the VivoTab with MM8 will of course be shown on the blog as well.