You can revert to default 76 MiB GPU memory btw, 512 MiB is complete overkill with recent kernel and just reduces the available system memory.
This doesn’t change something, does it?
sed -i -e '/rpivid-v4l2/d' -e 's/,cma-512$//' /boot/config.txt
reboot
On my RPi 2, Kodi starts up fine with startkodi from plain console, so at least on 32-bit I cannot replicate it either.