I have tried searching with something that has had the same problem to no avail.
I followed the instructions in https://shopify.dev/tutorials/customize-theme-add-size-chart and the size chart is not showing on my items
I want to show the jordan-size-chart when the vendor = Jordan. I have added the code to the three documents and am unable to see the size chart option.
I have changed the handle to jordan-size-chart.