Consistent with all mentions in this thread - I have to "end task" to close out Studio One 5 nearly every time I finish a session. I only use Kontakt 6 (full version) and audio files, so I'm not using anything too crazy. As for plug-ins, I use FabFilter and Izotope. Recently, I switched to Studio One 5 from Acid Pro 10, and I can tell you that all the plug-ins and Kontakt 6 work perfectly fine in Acid Pro 10, with no issues like I've experienced with Studio One 5. Thus, it seems to be the DAW's issue (Studio One's issue) and not 3rd party plug-ins...
Oh yeah, and I'd like to add something. Please, PreSonus, update the tiny user font of the user interface associated with Kontakt. It's like I need a magnifying glass to see what's going on, and I'm using a 32" screen. Thank you!