Image uploads broken in site editor

[glendaviesnz]

Description

In 17.1+ and trunk image uploads are broken via blocks in the site editor. The work as expected in post editor, and via the media library in the site editor, but using the Upload button in Image block etc. causes a Invalid paramater: post error.

It looks like this bug was introduced by #55970 - commits prior to this work as expected.

Step-by-step reproduction instructions

• Go to site editor and edit a page or template
• Add an Image block and try using the Upload option

Screenshots, screen recording, code snippet

Environment info

17.1+

Please confirm that you have searched existing issues in the repo.

Yes

Please confirm that you have tested with all plugins deactivated except Gutenberg.

Yes