From the Chart container for the respective chart, use the right side toolbar to 'save' the chart to a dedicated audit/chart folder on AIR-INSITE...

We've used the name 'SAMPLE SAVE IMAGE' to save the above chart (replacing the AIR-INSITE generated file name displayed above)...

Next, from within Publish Wizard, report container (we've created an empty report below).  Use the 'image' button on the toolbar...

Choose 'browse server' from the pop up window...

Then use the folders list to locate the saved image thumbnail and select it...

Click OK to close the image properties pop up and return to Publish Wizard where you will find the image...

Note: Depending on settings, you may need to edit the size of the chart image to ensure it remains within the margin guides.  To do this, either click on the image and edit its width and height properties or grab the bottom right of the image (indicated) and drag to suit.