The Error 10008 is a rendering error that is usually caused by some corruption somewhere in the project, although it might be hard to find. The black screen blips that you mention are indications of corruption. Removing and adding back in a corrupt clip will not change anything. But other things like mixed formats and positions of titles, incompatible frame rates, and so on can cause the issue. Or it can be project related, that can be cured by copy and pasting into a new project.
What format, resolution, and frame rate are the clips from your iPhone XS? What operating system and iMovie version are you using? Have you updated both? Try importing and sharing out media from a device other than your iPhone and see if the problem persists. Try importing a video from one of your sisters' phone, since they are not having the problem. Try using a video converter like the free download Handbrake to convert the clips to Mp4/AAC, even if they are already in that format. You can get Handbrake here:
https://handbrake.fr/
Take a look at this thread for some various solutions that have worked for others:
Help with iMovie- Error message 10008
Some solutions that have worked:
1. Create a duplicate of the project and export that.
2. Reposition titles. (Also can try changing the fonts in titles in case of a corrupted font.)
3. Convert your clips to .mov or Mp4 -- no mixed formats among clips.
4. At the point where the movie stops rendering, find that point in the project and remove some frames before and after.
5. Copy and paste the project into a new library.
6. Update both operating system and iMovie version to current.
Sorry you are having this trouble. Nothing to do but keep experimenting until you can pinpoint the point of corruption.
-- Rich
