Tempo syncing trouble

Hi, I'm experimenting with Moibus in stand alone mode and I'm having a hard time getting the loop timing to sync. When playing with a drum track, the loop I record in Mobius eventually drifts out of sync even though it starts perfectly timed. Is there a setting I may have over looked?

I'm using a Macbook Pro, running OSX Yosimite and my audio/midi interface is Focusrite Scarlett 6i6.


Thanks!