@codebard - I think we got it!!! 
I got on the phone with WP-Engine and the tech - who was incredibly helpful btw, which is why I use them - immediately knew what the issue was and we had it fixed in under 5 minutes.
WP-Engine caches very aggressively and that was causing the nonce not to be set properly.
For future WP Engine + Patreon Wordpress users who may stumble across this issue in the future: call WP-Engine and ask them to exclude the “patreon_nonce” cookie from the cache. They need the exact spelling of the cookie.
@codebard, maybe this could be included in the plugin documentation as well? I’m sure other wordpress-optimized hosting services do similar things with caching.
Finally, would you mind testing one last time on your end? https://straty.com/bitcoin/ Thanks
And thank you for all your work on this! I’m very appreciative!