Hey @acooke 
Welcome to the Community! Sorry you’re hitting trouble on this!
At first glance, I’m suspecting the invalid state appears to be related to those expiring state cookie notices in your console I’m seeing, but I’m not positive. I’m not sure why they’d be getting rejected as expired. 
That might just be how Firefox reports us purging them after verification, but it stands out. Let me see if I can duplicate this on my end.
Would it be possible to share the relevant portion of your code with me in a gist or repo so we can have a common baseline in our apps to work with?
Are you seeing this in browsers other than Firefox?