I'm having major issues with uploads that the video becomes out of sync with the sound with mobile devices. Clips play fine on Windows and OS X but as soon as I upload to Youtube to view on mobile devices, the video drifts out of sync (slows down) with the sound going on. But everything stays in sync on two computers with VLC, QuickTime and via the browser. I've checked many articles and Youtube videos on exporting for Youtube yet none of them solve the issues. As I'm now really stumped on what is wrong. Gameplay videos were recorded 60fps, mp4, H264. Exported mp4 and H264. Even checked to compare setting for Youtube. https://support.google.com/youtube/answer/1722171?hl=en-GB Totally at a loss what would be wrong. Restarted the iPad and iPhone both iOS 11.2.6, reinstalled Youtube apps. Tried many settings in Final Cut Pro and nothing solves it. Surely if the video was out of sync it would be on all devices, right?