Media removal. If Splice says a file or an asset is missing, this may be due to the removal of the related media from your Camera Roll. As Splice is currently not storing content locally, your photos and videos should always be saved on your Camera Roll to create and reproduce projects with the app.
What should I do?
1. Re-import such media back to your Camera Roll: this should allow your projects to be visible and editable again in Splice.
2. Turn off storage optimization on iCloud by following these steps: Settings > your name > iCloud > Photos > under iCloud Photos, select Download and Keep Originals
If you deleted the file recently, you might be able to recover it from the Recently Deleted folder on your device. If you backed up the file to a different location (such as iCloud), you can download it onto your phone once again, then add it back onto your timeline.
If you restricted access to Photos, go to your device’s Settings > Privacy > Photos > Splice and select All Photos. If you wish to share only a few assets, make sure you’ve selected the ones in your project by tapping Edit Selected Photos.