Using preference drive map to map shares.
Several GPOs each with various potential mappings (some filtered by item-level targeting) and several potential drives.
These drives are applied as "update" and "first available drive letter starting with X".

The issue is if a candidate user ends up with a drive of the same "starting with" letter from more than one GPO, the "first available" clause does not work in choosing a non-conflicting letter and they simply don't receive the second drive map.

Has anyone got this working (using replace, update, create...) properly?