Describe the bug
When editing any template, the header and footer stay in perpetual load mode and prevent any editing of those areas.

This bug is a result of responding to FSE Program Testing Call #1: Template Editing

To reproduce
Steps to reproduce the behavior:

1. Make sure you have the Gutenberg Plugin installed and are using TT1 Blocks Theme
2. Go to Site Editor
3. See the loading circles in lieu of the header and footer:

Expected behavior
To be able to see an editable block-version of the header and footer.

Editor version (please complete the following information):

• WordPress version: 5.6
• Does the website has Gutenberg plugin installed, or is it using the block editor that comes by default? Gutenberg plugin installed
• If the Gutenberg plugin is installed, which version is it? 9.7.1

Desktop (please complete the following information):

• OS: Mac OS 11.1
• Browser:Google Chrome
• Version: 87.0.4280.88

Additional context

• Template Editing otherwise seems to be working, although it's not particularly obvious that you are creating a change that will be implemented site-wide.