How was this resolved? I am having the same issue.
Line 264 of the plugin’s buzzsprout-podcasting.php has a hard-coded http:// the player will not appear on a site with HTTPS as long as that is in the plugin. You should do a check for environment, or remove the http: and just use “//domain.com”. The browser will automatically fill in the http/https.
Did you ever find a resolution to this?