The current pre-release of the client ("pioneer" in the version) is only compatible to itself. So you can only play with other testers. Please be aware!
The latest NVIDIA 460.79 drivers are causing this problem.
You can downgrade your drivers to 457.51 to fix it.
Please report it to NVIDIA in Geforce Experience or in their Forum:
https://www.nvidia.com/en-us/geforce/forums/game-ready-drivers/13/417924/geforce-46079-game-ready-driver-feedback-thread-re/