@worthlutz: Sorry, haven't got time to check this out for you, but maybe you can try this:
- copy the json to a static file on a server (something.json)
- point your proxy there
- see what happens if you remove elements that are not needed
This might not solve your problem directly (if you can't edit the service for example), but it might help the guys at Sencha figure this out if you can pinpoint what's causing the problem.
I have the same error with build 363 here you can recreate error:
- Create Json store
- Copy json file on root directory of designer project
- in proxy enter in url the name of json file (it's relative path)
- When i click load data in Store i have error JSON.stringify cannot serialize cyclic structures.
- If i put the complete URL: http://server/path/file.json it's work
- if i put a wrong file name in url field i have the same error