You can not have a list on a grouped output sheet.
You will know if you have this issue because the sheet will have a G number at the end of the KeyLAB name.
When you add a list to an output sheet the name will be for example ASTMStandardCompaction.Resutls_MoistureContent?G10. The G10 indicates that this cell is a list of 10 rows.
When a cell is grouped on an output sheet it will try and have the same G number at the end but this time It will try and start at 1.