Very Strange Audio/Video Desync

ChessChallenger Posts: 4 Just Starting Out*

Hey all. I have encountered an incredibly strange issue where the audio and video of my clips are desynced when I load the project, starting the process of resyncing them causes them to automatically resync correctly for timeline playback, but not for other, important functions. These include creating composite shots (the initial clip is still synced correctly, but pulling the composite shot from the media bin gives unsynced audio) as well as, crucially, exporting.

This is the only time I've ever experienced timeline playback and exporting not matching up correctly; I'd be inclined to think it's an exporting issue, but since the same problem is present with composite shots and because of some other stuff, I'm pretty sure something else is afoot. Notably, there's some strange flickering when I play through the timeline sometimes; it seems to flicker between the true location of the clip and the correct, synced location that isn't shown in export or composite shots.

First, and very importantly, I have constant frame rate video footage, confirmed in MediaInfo. I know audio desync issues can often be traced to variable frame rate, but that's not the culprit here. Additionally, the audio sample rates match, and everything should line up properly. I've done a similar process a few times before. If you would like me to provide MediaInfo screenshots, or any further technical information of that sort, just ask; I want this solved.

For my project, I recorded a video file of me speaking and also recorded audio separately on Audacity to be able to fiddle around with it more. I clapped twice at the beginning of the clip to be able to sync the audio easily in Hitfilm (or so I thought). I imported both clips to the timeline, synced them up to the precision of a frame, and started editing.

After about an hour, I wanted to export the first bit I had done (about a minute) to show my progress to a friend. I did so, but then found out the audio I synced using the above process was no longer synced, but audio from other clips I recorded was working properly. I reopened Hitfilm, and sure enough, the audio for all those shots was off. I copied the first part, stretched it back to the beginning of both clips where the claps were, and... Hitfilm froze for a bit, and then the audio was synced again. That first clip was synced for playback at the start of the timeline now as well, though other clips weren't.

To fix this, I decided to save the correctly synced footage and audio as a new composite shot, not edit it, and simply use it as a packaged shot to avoid this weird de-sync issue again. I'd lose most of my previous hour of work, but it would solve the problem. However, dragging this composite shot into the timeline had unsynced audio, despite the clip I had just used to create said composite shot matching perfectly. I was quite befuddled at this point.

I saved, closed, and reopened the project again. I messed around with the slip tool, but it's changes seemed to go away after closing the program, regardless of saving. Nothing seems to work. I'm sure there's other solutions to this problem, but frankly, I have no idea what is going on and just want a simple solution. Hitfilm is doing something really weird; I'm 99% sure this isn't user error. I recorded a screencap of all of this going on, didn't edit it at all (what would be the point of doctoring a proof video when you're asking for help), and uploaded it to YouTube, link

If there's any more information you need from me, or anything I should try, please let me know!

Processor: Intel Core i7-4790 CPU @ 3.60GHz

Installed RAM: 16GB

Graphics Card: GeForce GTX 1060 6GB (newest drivers)

Windows 10, 64 bit