Its a known issue that has been reported to the Github of Grief prevention. You can see it here.
https://github.com/MinecraftPortCentral/GriefPrevention/issues/921
You should be able to fix it by downgrading your sponge version
Edit:
Just seen this is a popular link now.
Grief Prevention is NO LONGER SUPPORTED and you shouldnt be downgrading your sponge version. Please use Grief Defender or a alternative source