Outlook doesn't group appointments by the custom labels created.

[Guest]

When you customize your labels for appointments in Outlook you can associate
specific colors to specific events such as: Doctor's instead of Must Travel,
or Lunch instead of Phone Call, etc... When you try to group by Label under
Active Appointments the old label meaning shows still. In other words, my
Lunch items appear under Phone Call still. This needs to be repaired as this
is misleading.

 

[Judy Gleeson]

A known problem - use Categories instead or keep a list of the original
Label names - I suggest Labels are only for Visual representation. If you
need more complex management than that, use categories.

Judy Gleeson