Hi - we're somewhat new to LTI development. We're trying to get the preview of a submitted assignment working in speed grader using the LTI 1.3 extension. Following https://canvas.instructure.com/doc/api/score.html#method.lti/ims/scores.create and looking at https://canvas.instructure.com/lti/submission - when trying to add this into the Grade, we see no errors but also nothing indicating it's trying to access the submission data. No preview shows up in speed grader.

Some potential questions that come to mind: 

1) for canvas.instructure.com/lti/submission, should we be using that literal url, or our domain? We have tried both but still see nothing

2) can you explain the different submission types a little more - "values are: none, basic_lti_launch, online_text_entry, external_tool, online_upload, or online_url" but when do we use external tool vs online_url or basic_lti_launch? I suspect this is not the problem yet because we're not seeing errors but it would still be helpful to know