It's true the Agent 4.8p3 and the future 5.0.2 release should support Windows 10.
What policies are not enforcing? Be aware that the Agent may be the only Windows 10 supported product at this time so no policies should enforce other than the Agent policies themselves. Do you have the 4.8p3 extensions for EPO checked in?
The basic ePO agent polices are not getting enforced as the ePO agent won't show up in the system tree. When I install the ePO Agent 5.0.1 then the agent shows up. One of the builds about a month ago did have the agent show up. However, it shows the policy interval at 5 minutes where we have it set for 30 minutes.
That is the opposite of what I would expect but obviously something has changed with the latest Windows 10 build since our testing was done with 4.8p3. Since we'll be able to test the official release once it is released to support we should be able to work out any bugs before it is RTW. At this point there is no other product that supports Windows 10 yet so a working Agent on a prerelease build may not be very helpful anyway.
We had the very same issue with Win10 and 4.8.3, the only way we could make it work was to install the 5.0.2 extension on the ePO.
Without that extension the agent 4.8.3 MA would install but nothing would happen after the installation as in no enforcement of any of the policies.
This is contrary to what McAfee says in their documents but i too could not get a answer as to why 4.8.3 without the extension would not work.