If the script contains 445 lines, you have 425 lines to delete. If the problem disappears while deleting some code, then you have likely found a location that is somehow related to reproducing the problem. Put the deleted part back in and delete other parts.

Most likely, the code around line 416 is related to reproducing the problem, so I would start by deleting lines 10 to 400 from the script and rewriting the rest so that it still reproduces the problem. We don't have your setup but it's highly unlikely that we can help you without reproducing your error.

Maybe you can also start by using the example program in Excel::Writer::XLSX and modifying it until it matches your code and still exhibits the problem.

A common case is that while reducing your program you find and correct the error.