It looks like a MOTU plug-in is causing this issue.
6 com.motu.driver.FWA.HALPlugin 0x0de631d4 PlugIn::RunLoopChanged(__CFRunLoop*) + 196
7 com.motu.driver.FWA.HALPlugin 0x0de6464d PlugIn::~PlugIn() + 45
8 com.motu.driver.FWA.HALPlugin 0x0de6302f PlugIn::Destroy::~Destroy() + 31
In case this is not the issue, please go into Studio One > Preferences > Advanced > Services and disable your ARA, AU, VST, VST3, and ReWire services. See if you can find a correlation to the crash and a particular service. This would help to identify the source of the problem.
With all the services disabled:
1. Enable a service, and test if the issue remains
2. Enable another service and test if the issue remains
3. Keep doing this until you find which service the issue lies in.
Once you can narrow down the service, it should be easy to find the culprit plug-in, that plug-in may need to be reinstalled or updated. Also, if that plug uses iLok or Pace, update the security too.
As far as Quicktime goes, Studio One 3 no longer has a Quicktime video service support. If you are not doing any video, you can also disable the Video Support service in Studio One > Preferences > Advanced > Services. Video Services
Try removing your settings from the program in the event that something is corrupt.
1. Go to Help>Open Settings folder.
2. Copy the contents of the folder over to a folder on your desktop.
3. Close S1 and delete the contents of the settings folder with the exception of the user.license file.
4. Open S1 and go to Studio One>Prerefences to reconfigure your settings.
5. Test to see if the problem is resolved. If it is not, please feel free to copy your settings files back over from the backup that you created in step 2.
*If you are missing presets or Sound Sets after doing this, simply double-click one of your Sound Sets under Documents>Studio One>Sound Sets.