[AC Question]

Im trying to change the lock screen image of my huawei p9 but when choosing both stock images from the gallery and wallpaper downloaded from the 'themes' app it fails to apply. However no error or anything comes up it says applying then when I lock the phone and unlock it to see if it's set it hasn't. However when setting both the home screen and lock screen together it works. Can anyone help me with this? I've tried factory resetting the phone but I'm not sure what I'm doing wrong my partner has the exact same phone and he hasn't had this problem at all. I really would like to change it independently of the home screen so any help would be appreciated!!