I came across an issue where the Offline Servicing for an OS image failed, and I couldnt get it to re-run successfully.
After a lot of research I found these commands helped to fully resolve the issue.
Run PowerShell as admin, then
change the path below to your appropriate path. The below is 1 line of code.
dism /unMount-Wim /MountDir:F:\ConfigMgr_OfflineImageServicing\ABC00288\ImageMountDir /discard