This looks like a bug I've seen with Jive previously when creating content. I don't think it has to do with any groups you've joined. Instead, I think it has to do with using the HTML functionality for posting. It's not something I've been able to resolve with Jive Support so far.
Try restarting your browser, trying using a different browser (Safari, Chrome, Firefox...), and see if any of that helps.
I've found that the problem spontaneously fixes itself over time so that eventually you can go back to using your normal browser.
We are working on an upgrade to Jive 8 and I'm hoping that this bug is one of the things that will be addressed.
Hope this helps --