Iframes inside bootstrap tab disappear when tab is shown

Your problem is not within your control. iframes are not your site (at least when embedding content from outside sources). The content there is under the control of some other developer. Then you have the problem that hiding and showing things using JavaScript can really mess things up – a common example is with Google Maps. The best you can do is to switch to plain links and enable oEmbed for that content as this is a slight and tiny bit more under your control and easier to handle than no control with iFrames. Then, you should perform something similar to an AJAX request (JS wise) and reload the contents when showing the tab/div/whatever-html-element. More info about that can be found in this answer.