Galaxy S8+ Slow Motion All Black!!!

[Maverick Offroad]

G'day everyone. I'm new to the forum so please forgive me if this isn't in the right section.

I've googled this like mad & not found a mention anywhere of my problem so I'm hoping you gurus can help me out.
I have an S8+ that I recently took a bunch of slow motion videos with. I edited the videos with the phone so the slow motion effect is where I need it in the videos, saved the videos & then exported them to my PC for further editing (I make YouTube vids). The problem is, when I open the videos I have exported to my PC, they are nothing but a black screen. Does anyone know what is going on & how I can fix it so I can use the videos? I need these videos in original quality & in a format I can run through my video editing software. Thanks in advance for any assistance.

 

[Rukbat]

If you need them in original quality, record them normally, then use software in your PC to make them slo-mo. See https://www.thewindowsclub.com/add-slow-motion-effect-videos-windows-10-photos-app