Answer
This behavior has differed across versions and patch levels, and whichever specific patch applies depends on your exact update level — rather than waiting on a specific patch to be identified and merged, you can trigger the same underlying grant process manually: Database_SYS.Grant_All_Objects_Ial is the method a delivery normally calls automatically to grant Custom Field and Custom LU tables to the IAL Owner, so running it manually forces those same grants immediately on your current environment, regardless of patch level.