Integrating Squarespace Websites Uploader in a form

Hi, I would like to integrate the Squarespace Website Uploader (https://www.squarewebsites.org/blog/squarespace-websites-uploader) in a form. You have to place the following script in the header.

Quote

<script src="//uploader.squarewebsites.org/sqs-form-upload.min.js"></script>

No sooner said than done. But when I tried to create the upload button in the form, it didn't appear. I tried the same procedure on my second website, and see: the button was displayed.

Why is this the case? Some basic information about the websites:

Website where the Upload Button works:
- Host is operated through Squarespace
- Template: Marquee
- Plan: Personnel

Website where the upload button does NOT work:
- Host is operated via external
- Template: Rally
- Plan: E-Commerce Advanced

Does it perhaps have something to do with version 7.1?

Example where the upload button does NOT work:

Example where the upload button does works:

Yes I need help with this as well. Commenting to follow post! 

In the meantime I could fix the problem. I have configured the language settings with German. After modifying it to English the button appeared.

This worked for me as well! Thanks!