My company has a procedure to remove and then re-add users with the same name during department transfers (this isn't best practice I guess?).
Presently, the user has problems accessing files in the document library which has been granted to her account by the owner of the document library.
We have configured incremental sync for the user profile service application during the initial farm setup.
Could the above be related to the old IDs (in Sharepoint) not getting updated in the user profile sync?