query filter not working as expected

I have this code which I use to query task report. I want the filter to check if the asignee groups are in an array of input groups. Take a look at the working example first:

a!queryProcessAnalytics(
    report: cons!GBD_Report,
    contextProcessModels: cons!GBD_Process,                                      
    query: a!query(
      pagingInfo: a!pagingInfo(
        startIndex: 1,
        batchSize: 100,
      sort: a!sortInfo(                                          
        field: "c2",                                             
        ascending: true                                          
        ),    
      ),
    filter: a!queryFilter(
        field: "c4",
        operator: "=",
        value: ri!group
      )
    ),
  ),

This works because ri!group is not an array but a single group. However when I turn the ri!group into an array of groups, and instead of operator "=" use operator "in" so basically check if group is IN an array of groups I get no data. If I use "not in" operator I get the opposite - I get all tasks. What is the issue here?