How to format the data "task_assignee_owner()" or "tp!assignees"?

hi all, i'm using function "getPortalReportDatasubset" to get task data from portal report.
my question is how to format the data?

for example, how to format the data "task_assignee_owner()" or "tp!assignees"?
in portal report, we select the built-in format " User or Group Name" in report configuration.
in sail, it shows [Group:35] if we don't format it.
and if i user function "groups(local!datasubset.data[2].cells.value,"groupName")" to format it, it throws error:The passed parameter(s) are of the wrong type.

i guess this because "local!datasubset.data[2].cells.value" is a group list of list.

below is the "Task Assignee" column.

a!gridTextColumn(
label: local!datasubset.columns[2].label,
field: local!datasubset.columns[2].field,
data: if(
local!datasubset.totalCount=0,
{},
local!datasubset.data[2].cells.value
),
alignment: local!da...

OriginalPostID-137258

OriginalPostID-137258