Unstable - Getting 'Page not found' at the channel editor

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Observed behavior

Observed while testing https://github.com/learningequality/studio/pull/5750:

I'm frequently getting a 520 error 'Page not found' at the channel editor.

https://github.com/user-attachments/assets/fc1f56d1-97ab-4022-b719-a5aecc200bb7

Expected behavior

It should be investigating what's causing the error as it happens on various interactions without an obvious cause.

Steps to reproduce the issue

1. Sign in to Studio at Unstable
2. Create a new channel, import content and publish it.
3. Click the Share button, select the Submit to community library option and submit the form.
4. Navigate to a different channel and back to the current one.

Usage Details

• Studio Unstable
• OS: Windows 11
• Browser: Chrome, Firefox

Begin with the reproduction steps in this issue on Studio Unstable, especially submitting to the community library and returning to the channel. Trace the channel-editor navigation and submission flow to identify why a 520/Page not found occurs across interactions. Done means the listed workflow completes without the error.