In your excel application scope you can use the “Get workbook sheets” activity. Save the output to a list<string>
variable I’ll call xlSheets. Then in your if statement it should be if xlSheets.contains(“YourSheetName”)
I see your edit now, it looks like you already tried this. The above code works fine for me, can you do a for each loop over your list of strings and use write line to output the results? Make sure the output is what you expect