Do you have iCloud photo library enabled? If so there can sometimes be an issue with connecting to iCloud which can cause transfer failures. If you see All photos when you access the native photos app iCloud photo library is enabled. A couple of things you can try
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Ensure you have a valid internet connection. If you are using WiFi try LTE and if you are using LTE try wifi
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Try turning off iCloud photo library and attempt to re-transfer the files. See if you see the same failed message
