I activated Hummingbird and started getting the 405 errors in my attached screenshot. I was able to deactivate a bunch of plugins, flush my browser, SuperCache, Cloudflare and server Varnish caches and eliminate the errors. When I reactivated Hummingbird the problems returned. Now, however, none of my attempts to remove the errors are working. Note that I see the errors on Mac Chrome but not Mac Safari. Please advise.