ID 377253 - Compare tool doesn't find revisions from the sequence of episodic shows. Trying to force a compare will break the client.

Steps to reproduce

- Create/open an episodic show with at least one sequence made up of multiple revisions with multiple panels. 
- Open a revision from the sequence and click on the compare tool. 
- Click 'COMPARE'. 

Expected outcome

- All revisions from the sequence should be listed in the 'Compare Revision' modal. And the 'COMPARE' button should not break the client. 

Actual outcome

- No revisions from the sequence are listed in the 'Compare Revision' modal. And the 'COMPARE' button breaks the client. 

See video attached and screenshot for error message. 

Tested on MacOS 10.14 and Windows 10. Flix pipeline, develop_171.