Grouping variant &1 is inconsistent

What causes this issue?

The <DS:DE.BILL_GRVAR_KK>grouping variant</> &v1& is inconsistent.

System Response

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

How to fix this error?

Check the attributes of the grouping variant. The following consistency
requirements apply to grouping variants, if the
<DS:DE.BILL_GRULG_AGGR_KK>Aggregation Behavior of Characteristic Values
</> field contains a value other than SPACE:
The <DS:DE.BILL_GRNAM_KK>grouping characteristic</> has to be a customer
field. That means that the field has to be contained in customer include
CI_FKKBIX_BILLITEM_IT.
For the option <LS>Do Not Total (2)</> you have to ensure that the
original value of the grouping characteristic is unique for each group
created. To do so, choose the option <LS>Use original field value if no
alternative value defined</> (SPACE) in the <DS:DE.BILL_GRULG_KK>Use of
Characteristic Values</> field, and do not enter any alternative values
for this characteristic under <LS>Assign Alternative Grouping Values</>.
In the current case, consistency requirement &v2& for grouping
characteristics &v3& is violated.

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.