Hello,
Make sure you are running the Latest version of SEP 12.1 RU2
Secondly, I would suggest you to perform this Steps provided below:
1. Create a new group in SEPM
2. Assign to this new group same policies than impacted group. It is possible to use "Copy/Paste policy" feature by right-clicking on groups, as it it not copying corrupted installation package
3. Move clients from impacted group to the new one
4. Reinstall all clients from the new group or use "Installation Package" tab to install back appropriate features
It is recommended to remove the installation package assigned to the new group once all clients will be using correct features, in order to ensure this problem will not reappear.
I would also suggest you to follow these 2 Articles below:
http://www.symantec.com/docs/TECH164677
http://www.symantec.com/docs/TECH93564
Hope that helps!!