Document References are not properly uploading during Project Creation when required fields are initially missing information and later corrected.
The problem is not 100% reproducible. The highest chance to reproduce is, when the last edited attribute before user clicks the "Save" button is configured to trigger attribute category visibility rule and/or JS Button functionality. These actions result in redraw of the whole attribute category almost at the same moment as the submit of the page is initiated. In such a scenario there is a relatively high chance that the submit of the page happens just after redraw of the first/root level attribute category, but before descendant attribute categories (of documents referenced by document reference attributes) are fully re-created and rendered. As a result, the values of attributes in the descendant categories might not be saved as they are not part of the HTML form submitted with the page.