Pretty sure the root cause is the blend of http/https sources. Chrome and perhaps other browsers helpfully block the http content some of which is probably need

Pretty sure the root cause is the blend of http/https sources. Chrome and perhaps other browsers helpfully block the http content some of which is probably needed for the webpage to function. In Chrome you click the shield icon next to the bookmarks star in the address bar. I believe the page will then reload showing the http content which will usually fix the issue. I say "helpful" un-ironically above because the http content can compromise whatever is on the page. The OP is of course right that the developer of this page is dangerously incompetent.