problem with writing dataframe to excel with xlwings

Question

I have a working script for some financial modeling . The script reads inputs from couple of sheets from the excel and returns a dataframe. When I run the script and print, the dataframe looks fine. But when I try to write the dataframe to the excel file, it throws an error.

I have tried the same chunk of code (that writes to excel file) separately and it works flawlessly. Not sure what I am doing wrong.

the actual code is quite long, so here is the final snippet: NOTE: the values in the dictionary are the lists that are defined inside the code, so i hope that is not what creating the issue because without the commented part(writing to excel), the code runs perfectly.

def main_function(filename):
    output_df = pd.DataFrame({
                'Stage': n_stageName,
                'Year After Origination': n_yearAfterOrigination,
                'Management Overlay': n_mgmt_overlay,
                'PD curve ID': n_pd_curveID,
                'LGD': n_LGD,
                'ECL': n_ECL,
                'FLI Adj ECL': n_FLI_adj_ECL,
                'EIR': n_EIR,
                'ECL (JMD)': n_ECL_JMD,
                'FLI Adj ECL (JMD)': n_FLI_adj_ECL_JMD,
                'Exposure': n_Exposure})

        #ws = xw.Book(filename).sheets['test']
        #ws["A1"].options(pd.DataFrame, header=False, index=False, expand='table').value = output_df

       return output_df

main_loop('sample2.xlsx')

however, when i run the same chunk of code for writing into excel on a separate file (where I created a dataframe manually), it works fine

def to_excel(filename):
    output_df = pd.DataFrame({
            'Stage': [1,2,3],
            'Year After Origination': [4,5,6],
            'Management Overlay': [7,8,9],
        })
    ws = xw.Book(filename).sheets["test"]
    ws["A1"].options(pd.DataFrame, header=True, index=False, expand='table').value = output_df
    return output_df

to_excel('sample2.xlsx')