iFrame problem in spoiler still not resolved

Hi,

I’m having a bandcamp (it’s like soundcloud) iframe-embed in a spoiler box. but not in an active tab. which is the reason why the content is not loaded properly. Take a look for youself and click the “Releases”-Tab:

http://lesterdudit.net/v1/#doc-foster-band

If I set active=4 it works, (but the embed on the first tab not really) …

Would be awesome to get some help on this glitch.
Best,
Steven

https://wordpress.org/plugins/shortcodes-ultimate/