After upgrading to 3.1, you don't see any groups presented in the Group Inclusion configuration dialog box.
The ATP appliance only retrieved a small number of groups when checking with the Symantec Endpoint Protection Manager (SEPM). ATP 3.2 will download the list in larger chunks so the data is loaded quickly.
This issue is resolved in ATP 3.2. If you cannot update in a timely manner, please contact support to have a hotfix applied to ATP 3.1.