Hi Ziyad,
Can you please check the status of the DFSR by running this command and providing the output
dfsrmig.exe /getglobalstate
If the result shows: 3 (ELIMINATED) ,it means DFSR
Also the DC Health status will be good to know before we proceed with investigation.
Dcdiag /v >c:\dcdiag1.log
Repadmin /showrepl >C:\repl.txt
Repadmin /syncall /APeD
As a test can you create a new Win10 GPO with some settings and apply on the device, proceed to run the GPUpdate /force on the client and check whether this GPO has been applied succesfully. If it does apply it means replication and DFSR is working and the original GPO is corrupted or having read permissions issue.