I have about 20Gb worth of photos and videos in my iCloud Photo Library (as reported by various devices when I look in the iCloud management tab). For some reason however, both my iPad and iPhone are both using twice as much for photos. If I look in the settings tab, they both correct the correct amount, but when connected to my Mac, iTunes is reporting over 40Gb of space used. If I turn off iCloud Photo Library and delete all photos, all 40Gb are reclaimed, but turning it back on (with the keep originals on device setting) immediately claims up 20Gb, which then gradually expands to 40 (as reported by iTunes) as originals are being downloaded. I normally would not trust iTunes in this case, but the odd thing is that although my iOS devices report the correct amount of space used by photos, the total amount of free space is short by 20Gb (exactly the amount iTunes is claiming also belongs to photos). Has anyone experienced this before? P.s. I have tried restore my devices, but the behaviour is always the same.