If you've installed a rooted image like I did, maybe you just noticed that the author decided to get rid of LG bloatwares. But some apps are really useful and I don't get why he removed them. I am indeed refering to FM Radio and Quick...
Forgot to update. Latest version (MM). :p
Found the culprit. Better late than never. One of the mod is bugged.
Open H-Settings app > Others > Visualizer > uncheck 'Enable visualiser on lockscreen'. Then reboot. And voilà..
Did some testing and now SystemUI is not crashing on lockscreen ...
GravityBox is now fully compatible with Xposed for Nougat! I hope it will make the port of G4 TweaksBox easier.