Microsoft has released a very important hotfix for FIM2010 R2 SP1: full details at https://support.microsoft.com/kb/3048056. (FIM Build 4.1.3634.0)
As indicated in the article, Microsoft recommends that all customers apply this update to their production systems.
The most important fix in this hotfix is that FIM2010 R2 (SP1) now fully supports Windows Server 2012 R2 Active Directory Domain Services, both for domain and forest level.
Still an important condition for this support is that the FIM Synchronization Service must be installed only on
- Windows Server 2008,
- Windows Server 2008 R2,
- or Windows Server 2012 member server.
FIM 2010 Server components must NOT be installed on a Windows Server 2012 R2 member server.
Only the PCNS component can be installed on a Windows Server 2012 R2 domain controller.