I had the same problem and could resolve it on this way
EXAMPLE
[su_spoiler title=”Main” style=”fancy” open=”yes”]
[su_accordion]
[su_spoiler title=”Here you can add your headline”]
The content for the spoiler[_/su_spoiler]
[su_spoiler title=”Here you can add your second headline”]
The content for the second spoiler[_/su_spoiler]
[/su_accordion]
[/su_spoiler]
