Hi, Josh.
Same issue here. My wordpress site just started blocking out validated users and now I the only error message I get is “There was a problem with your log in: Invalid state [error code: unknown]” I’ve followed all of the steps and I’m working with my hosting company exclude the cookie from being cached, but my issue is that it works on my staging server and not my production server. My staging server has no issues, but the production server just stopped working altogether when it was working fine up until yesterday… need some help please. Thanks.