I am facing issue with expression based Borderstyle and BorderColor in Excel Export only whereas same expression is working as expected in web browser, PDF export and report designer. In Detail row-group, row is using expression based Borderstyle to show border "Solid" or "None" but Excel export is completely omitting the expression.
for bottom border Color =IIF(Fields!Show_Underline.Value=1,"Black","White")
for bottom border Style =IIF(Fields!Show_Underline.Value=1,"Solid","None")
Please see below screenshots
Report Output in web browser, PDF export and report designer
Report Output in EXCEL
Sample RDL location:
https://drive.google.com/file/d/1MgWExAQqUu2QYBaO4mvZ5QoNV16ob0UB/view?usp=sharing