Cannot use cover image or gallery blocks with roles such as author in a single install or editor/admin in multisite

[miguelurtado]

Describe the bug
The blocks Cover and Galerry Images only work with editor and administrator role. In multisite only work with super administrator.

To Reproduce
Steps to reproduce the behavior:

1. Go to admin posts with author role and create new post.
2. Click on new block > select Cover Image > configure the block > save the post.
3. Open the post in front end view
4. Update (F5) the post edit page.
5. See error (image print)

Expected behavior
A clear and concise description of what you expected to happen.

Screenshots

Desktop (please complete the following information):

• OS: Windows
• Browser Chrome
• Version 69.0.3497.100

[designsimply]

Good find! Tested and confirmed using the author role on a site running WordPress 4.9.8 and Gutenberg 3.9.0-rc.2 tested with Firefox 62.0 on macOS 10.13.6.

API request for the media during editing:

http://alittletestblog.com/wp-json/wp/v2/media/14063?context=edit

API response:

{"code":"rest_forbidden_context","message":"Sorry, you are not allowed to edit this post.","data":{"status":403}}

[aduth]

Partial duplicate of #2539

The error response of @designsimply 's comment is related, though not quite the same as in #2539 which is mostly about block invalidations caused by content sanitization.

[miguelurtado]

Hello @aduth
Thanks for reply, this related of unfiltered_html capacity.

[mtias]

This should be addressed with https://core.trac.wordpress.org/changeset/43781