OfficeJS缓存

I'm really curious if someone can better explain the internal workings of excel's addin caching of javascript functions? I'm running a flask app on my own internal website behind a SSL cert. My addin pulls in this functionfile.html, and makes an ajax call back to mysite:

<script>
// After the Office library builds, it will look for Office.initialize
// which must be passed a function.  It doesnt have to do anything though.
    Office.initialize = function (reason){
        $(document).ready(function(){
            registerBindings();
        });
    }


    function getData(){
        return Excel.run( function (context) {

            // request bindings
            var state_nbr = context.workbook.bindings.getItem("state_nbr").getRange().load("values");
            // and the rest for the ajax call

            return context.sync().then( function () {
                $.ajax({
                  type: "GET",
                  url: "https://example.com/excel/function",
                  data: {
                      "state_nbr": state_nbr.values[0][0]
                  }
              }).done( function (data){
                      context.workbook.bindings.getItem("test").getRange().values = [["done"]];
                      return context.sync();
              }).fail( function (result){
                      context.workbook.bindings.getItem("test").getRange().values = [["fail"]];
                      return context.sync();
              });
          });
      });
   }
</script>

When I click my button, I can see the request with the right payload going to example.com/excel/function, which is a flask route that pumps out a bunch of CLI junk (hundreds of logging commands).

What gets weird though, is that after that first click every time I click the button I don't get any new ajax requests, I only get a request for the functionfile.html. But SheetA1 still pops up "done".

I thought this was just storing the results in cache, but even with flask running in debug mode, if I change functionfile.html, say [["done"]] to [["finished"]], no new ajax call is detected in my logs. BUT THE SHEET UPDATES?!