Sorry, you're encountering this issue. We've been trying to understand what is causing the problem.
As of now, it seems that the issue is happening only with HEVC or what Apple calls "High Efficiency" format. If you go to Settings > Camera > Formats and change the setting to "Most Compatible". You should not see the issues when your clips are captured in that format.
We're working to resolve this now. In the meantime
- Record your clips using the "Most Compatible" setting
2. Export your project from a desktop computer (mac or windows).