You should understand that Power KPI Matrix is designed to show current value (the latest one) in comparison to planned value and sparklines help to see how this value was changing over time.
Therefore, if your dataset has only one record for a metric, there will not be a sparkline for this metric.
The average value is just a number, it doesn't have any dynamic.
So, it seems that you try to use the visual with inappropriate way.
Microsoft Power BI Custom Visuals