It is not recommended to have Clients of higher Version than the Manager. Migrate your SEPM to RU6a to RU6MP2 and it should be fine.

The Manager should always be equal to or higher than the version of the SEP clients it manages.

Best practice says to have both the SEPM and clients on the same version. At the very least the SEPM should be at the same or higher version that the clients. I've seen issues with clients on a higher version than the SEPM.

Is your GUP getting the updates from the SEPM?

There were major changes to GUPs in RU6 and the clients are going to be looking for completely different policies to define the GUPs (globallist.xml). Your SEPM needs to be migrated to match the version of your clients.

Hello,

Best Practice to Resolve this issue is you Migrate the Symantec Endpoint Protection Manager to the 11.0.6005 (Ru6a) first and then Migrate the same to the Latest version of 11.0.6200 (RU6 MP2).

a) Migrating to Symantec Endpoint Protection 11.0 RU6a

http://service1.symantec.com/support/ent-security.nsf/854fa02b4f5013678825731a007d06af/6f5427dfdd4a0cc18825770400611b5a?OpenDocument

Then , Migrate the SEP clients to the Latest version.

There are lots of Issues Fixed within this versions. Architecture of GUP is changed as well. Check the following. check the following:

Release notes for Symantec Endpoint Protection 11.0.x and Symantec Network Access Control 11.0.x