Hi newbie user but have sucessfully completed a few projects but have tried to export a project which features bits with 3 and four split screens, which all work well when i run the preview through from begining to end but when i export it for instance in 3 horizontal screens the 3rd one is blank, checked preview and tried exporting again but the same. im using a decent i7 processor 16gb ram plenty of disc space, any help please.