I was having problems with modification of a remote site , specifically installing and configuring OS Deployment Components.  I had a previous replication policy configured when testing this feature when it was first released.  The symptoms i had experienced: I was unable save OS Deployment Components settings nor would the settings create an image or driver repository profile when saving modified remote site.

After working a case with support, the cause was that I had deleted a previously assigned replication policy before it was changed in remote site to a new or existing replication policy.

So don't do that :)

Just wanted to give a heads up.