1. Packages are not copied to DP due to lack of permissions, pls check the necessary rights.
2. Check for package on affected DP whether it's present or not.
3. If not, check distmgr.log file on affected DP and manually copy .pck file from primary server to affected DPs and use PreloadPkgOnSite.exe tool to replicate package information to SCCM database.
here's info regarding this tool-
4. If package is present on DP but not updated to database or SCCM console; refresh DP again.
5. If still DPs not updated, try run these queries for affected DPs through central server-
update pkgstatus set Status = 2 where id = '
update pkgstatus set SourceVersion = 0 where id = '
6. After running above queries, refresh DPs again.