Random lag when locking / unlocking

Hi, I got my Elephone p9000 about a month ago and it's been running perfectly fine until the last few days. When I leave the phone locked for a while, and I try to unlock with my fingerprint, it will occasionally refuse to acknowledge i've placed my finger on the scanner, it can take up to 5 or 6 seconds until it unlocks, almost as if theres some kind of lag while the phone is asleep. This extends to locking the phone, if i'm in an app or on my home screen; and press the power button to lock the phone, sometimes it will just turn off the screen, not actually lock the phone, until 5 or 6 seconds later again, when I hear the lock noise and I'm back on the lock screen.

I've not changed anything, this has just started happening in the last week. If anyone has any ideas, i'd be very grateful for any help.

Thanks,
Holt

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