Turn off saving battery power in photo to continue to upload to iCloud

I have an iPhone 6 plus, 128 GB, and I have been uploading my photos to iCloud. Until recently my photos have been uploading to the iCloud and using a combination of wifi and mobile data when I was away from wifi. I have since turned off my mobile data within the photo app so that it does use the wifi. However now, when I go into photos it says "upload pauses for 1680 items", Resume (is in blue) which I then tap to resume, and not highlighted it says "saving battery power", which I am not in the low power mode. After tapping resume, it does nothing. If I turn off the mobile data to restrict to wifi within the photo setting it will work. But I don't want to use mobile data, given the amount of photos.