The issue with your MicroChart in Power BI Report Server could be due to the fact that MicroCharts are not supported in Power BI Report Server. MicroCharts are a feature of Power BI Service and Power BI Desktop, but are not available in Power BI Report Server.
As an alternative, you can use a standard visual, such as a bar chart or column chart, to display your data. To create a bar chart or column chart, follow these steps:
Select the data that you want to use in the chart.
Go to the "Visualizations" pane and select the bar chart or column chart icon.
Drag the desired fields to the appropriate sections of the chart (such as the X axis and Y axis).
Adjust the formatting and style of the chart as desired.
This should allow you to display your data in Power BI Report Server, even though MicroCharts are not supported.