How do I get raw urls with contextual filters to work with views in Drupal 7, when i'm using panels, and panels everywhere?
Try using argument 2 (URL arguments start at 0 not 1) as opposed to argument 3. A Failing that, disable the validation, oftentimes the validation is screwy and excludes valid content.  Start with as little filtering, validation, exclusion, etc. to make sure you're getting data and tighten the parameters from there.