I've had this problem quite often. For me, it's often to do with the maps I've created so I'm forced to delete any recent ones I've made and then restart my computer.
It normally fixes the problem, but I've not made many maps before so as Buffy said, try switching your rendering system to Direct3D9. And if that doesn't work, I'm honestly stuck with how to help you. D:
You never know though, It could be something really silly and easy to fix c:
Good luck ^.^
~Nym