Hey there calarttech! The multi-day event cutoff in 3.0 is located under the Events -> Settings -> General tab. It’s actually been renamed to the End Of Day cutoff and can be seen here: http://d.pr/i/eNgC.
That said, we do have a bug with it not functioning properly in the current release. This should be fixed in an impending maintenance release and we appreciate your patience on this end until then. If I can do anything else, or if you have other questions, please let me know.