NOTE: this guide is only relevant for those who installed the app through Shopify's app store!

The issue:

There are certain code the app adds to your theme and these changes are not carried over when you change themes.

The fix:

Please click on "Help" button from the dashboard pageĀ in the app. Scroll down in the dropdown and click on the option "Install code snippet to new theme". Make sure you are on the dashboard page since the help dropdown is different on each pages.

That's it! Your size charts should be back and running.