I've created a slidehow on a Mac in LR and have been tryig to synch a music fie to the slideshow. The music fies are resident on my computer. The files about 14 minutes of music have not succesfuly synched after 10 mins and I have therefore abandoned the effort . Why is it so problematic the synch music filles in the slideshow. In Apples old Aperture application it was practically instantaneous.