This is because Dropdown and Table are of array datatype, not string like all other values in your JSON data. Thus, when saving data to webhook, an error occurs if you define array as string (put it in double quotes) like so:
"Table": "{{Table}}"
For the data to be pulled through correctly, any array values should be placed without double quotes as follows:
Here, you should paste a sample of your raw JSON payload (input data). It is the data that you use to populate the template or to test it. Simply put, you should replace {{Table}} with an array of data like so:
Did you manage to input this JSON into the window to generate the schema? If the schema has been generated fine, is the data not getting through to Power Automate, or is it something else?
I've added a few of table values from the HTTP trigger to the excel part and the flow fails. I've tried one a few different table values and the flow still fails:
What if you generate the schema from a JSON without the Table array and then apply it to the Excel action? Is there any result?
Btw, if you just put static values in the Excel action, does it generate a correct Excel file? If yes, try to add some dynamic values one by one and check when it starts to fail to add the data to the result excel file.