Having read and re-read the posts and referred articles by ITGURU and Arthur (no relation) from Dec last year I must come to the conclusion that W10 Ent and W10 Edu work differently. We have Start Menu re-directed in the old way to a network share - it's been like that since folder redirection was invented, and the entries in the All Apps start menu which were used to pin the Start Screen tiles are shortcuts from there (at least THAT still works!). The articles all state that the All Apps "database" is populated at boot-up, from the "$allusersprofile%" path and the user's %appdata% profile path, but how can this be true as at that time the system doesn't know which user will log on (especially on a network, but even with multiple local users), and %appdata% will not be set. I'm not convinced. In any case, we find it is taking shortcuts from the re-directed start menu folder in Ent but not in Edu. So ...
I copied the shortcuts from the network share into %alluserprofile%\microsoft\windows\start menu\programs and pinned some to Start Screen (the targets of the shortcuts are in the PC's Program Files). Still nothing shows for a Teacher user (which has a policy with "Remove common program groups from Start Menu" disabled). I then thought I'd start from first principles. Logged on as a local admin I see the "Default" Start Scren which consists of as-supplied tiles for e.g. Edge, Photos, Calendar etc. but no installed programs. I exported that Start Screen. Breakthrough? - that shows the as-supplied tiles for a Teacher user. Hooray - progress I thought. Then, back as the local Admin, I pinned some programs that appear in the All Apps list to the default Start Screen, but they DON'T appear for the Teacher. I added a tile for Calculator and that did show up. Grrrrrrrrrrrrr.
Just as an aside, although we have the Start Screen XML files on the DC sysvol, I have tried it with the file on the PC's C: with the same results, and yes, I have also tried deleting the user's roaming profile (and we delete cached copies of roaming profiles from the PCs after logoff).
Conclusion so far - Microsoft don't want you to be able to pin any installed programs to a common Start Screen.
I really can't understand how anybody has got this to work. Please somebody prove me wrong?