Script to convert base64 to image in Excel not working

This is a cross post from the Power Platform Community, as i'm not sure where is best to ask my question.

This suggests the problem lies in line 6 of the script. Unfortunately, I'm not an expert, and the last time i played with Excel scripts was over a decade ago with VBA rather than Office Scripts. I have tried playing with it in as far as i can, but nothing seems to offer any success. To me, the script actually appears fine, and it seemingly worked for others according to the other thread. As the base64 script is correct (and doesn't include the data: or /png etc), I'm left bewildered and hoping that someone can spot where i've gone wrong (that person will have my eternal gratitude!). Script included below

 

function main(workbook: ExcelScript.Workbook, base64ImageString1:string, base64ImageString2:string) 
{
   const sheet = workbook.getWorksheet("Output");
   const range1 = sheet.getRange("C43");
   const range2 = sheet.getRange("I43");   
   let image1 = sheet.addImage(base64ImageString1);
	    image1.setTop(range1.getTop());
	    image1.setLeft(range1.getLeft());
	    image1.setWidth(range1.getWidth());
	    image1.setHeight(range1.getHeight());
	    image1.setPlacement(ExcelScript.Placement.twoCell);
   let image2 = sheet.addImage(base64ImageString2);
		image2.setTop(range2.getTop());
		image2.setLeft(range2.getLeft());
		image2.setWidth(range2.getWidth());
		image2.setHeight(range2.getHeight());
		image2.setPlacement(ExcelScript.Placement.twoCell);
}