Some photos not uploading to iCloud photo library
I uploaded 16,000+ photos to iCloud photo library. But now I found 100 photos (JPGS) in a dedicated folder called "Upload not possible". Those 100 photos seem to have been removed from their albums during the upload process.
My first measure was to free up some space on my iPad. I now have 30 GB of free space on the iPad. In iCloud I have 10 GB free space.
Is there a way to get those 100 photos synced to iCloud?
I put a few of them back in their albums, but that does not trigger a sync either.
iMac, macOS Sierra (10.12.2), Retina 5K, late 2014