Yes, I had the same issue, this is a bug in all fw version. I did contact dlink support but no answer.
The dhcppd is not working properly. If you want to get it working :
Enable ULA, reboot the router, disable ULA. ULA is in local ipv6 local settings.
To avoid router reboot, change to stateless, aply, enable ula aply change back to stateful aply and disable ula. This way you only restart the dhcppd service.
I'm about to sell mine, this bug and no hardware offload make this device a waste of good hardware.