I'm having a trouble using Omnisphere 2 with my Studio One 3. For a while it works perfectly, CPU load is OK (no crackling sounds or anything, actually lower than expected), the VST itself sounds absolutely fantastic and everything works like it should.
Then suddenly, in the middle of browsing factory presets, as soon as I change the preset it will get stuck on the previous preset and won't allow me to change it anymore. No sound comes out from Omnisphere 2. It seems to function (I can use knobs and browse menus) but no sound and I can't change the preset. WHEN I try to remove the instrument and track, my Studio One crashes. I have to kill the process from Task Manager and wait for a bit before it fully kills the program and restart Studio One.

I'm using the latest version of both softwares. The problem started as soon as I installed Omnisphere 2, and only when I'm using it. Any other VST have been working fine for me (expect some JBridged vsts, but I can live with that)

 

Since you said omnisphere 2 it was working perfectly , try to remember what the last thing you did before omnisphere 2 caused S1 to crash
and by knowing it you can undo it or you can Fully uninstall "S1 & Omnisphere 2" & Keep The Steam Folder and do clean install and see if it working

 

I have noticed omnisphere occasionally stops whilst changing presets, however if you just wait a minute or two it will start again

win7 64bit / omnisphere v2

 

You will see an Omnisphere update soon

 

I need to try that one again next time it freezes, I waited about 5 mins I think but it didn't do anything.

 

could be an S1 problem, I have also noticed S1 pausing when adding a new midi / instrument track, I play a few notes and S1 will stop / pause for about 30 seconds, after that everything is ok, v2.6 doesn't do this

 

Try using another audio driver. I find some trouble between s1 v3 and asio4all.