I've already brought the issue up to the team, but in the meatime we can try multiple things to solve your problem.
First, go to your Preferences > General > Material Preview Shader and switch the preview shader to pbr-metal-rough-with-alpha-test (if it already is, try to remove it and reload Substance Painter).
In addition, you may try to update your graphic card driver (always good to check).
And if those don't work, send me your log (help > export log...) so I can dig deeper into your issue.
Let me know !
Cyril Dellenbach (Micro) | QA Support Artist | Adobe