I am  using Report builder to create MS Excel documents from an MS Excel template.  I am using Excel for Mac version 16.38.

The template I upload contains someconditional formatting on certain fields.  (Subject to value of the filed the conditional format only sets the colour fill and makes the font bold).  I am doing this os that I concrete in MS Excel report formats that match what I have been able to produce on screen using WpDatatables.

The file the Report Builder produces is populating my fields OK and setting the colour correctly.  However  the font is changing to Cambria size10.  I appreciate that this may be an MS issue. Indeed, my research suggests that this issue may  be caused by saving the Excel file as an earlier format ( 97-2004 for example).  I am not saving the template file I upload in such an earlier format.  I am wondering if, in the background, Report Builder is saving/converting or produing the xlsx files in an such an earlier MS Excel format?

If it is converting/creating the excel files in an earlier format is there a way to change this?  Its frustrating that Wp Datatables produces great colour coded tables that Report builder can then replicate into downloadable MS Exel formats only for the conditional formatted cells to have the font arbitrarily changed.    

I would be grateful if you could advise please.

I accept that it may not be coming from reporters builder. I am just trying to establish if Report builder is in any way saving/converting excel files into older versions.  I am aware that the bug I have described can be caused by saving a document in an older version of excel and then back again.  I just thought that in order to maximise historical compatibility Report builder may have ensured that it was compatible with using older versions of Excel. 

I guess the the thrust of my question is, What is the oldest version of MS Excel that Report Builder is designed to be compatible with?