Hi Eli,
Did you by any chance miss to do the Work Center Page Configuration to show these groups ?
Or
Did you miss creating your Component usage for the component CRMCMP_GS_WC and adding the Interface View IFVGroupLinks to work center page you created in Runtime Repository
If you are not aware of this, here is a component to refer WCC_SLS_ACT.
Activities work center in standard SALESPRO role is shown from this component.
Regards
Vinod