How To Track “Submission rejected, token invalid”

Thanks in advance. I’ve been using Caldera forms for a while now and it’s great. Recently though this error has been intermittently occurring which is impacting visitors without us knowing.

How can I setup something to keep track of occurrences of this error, preferably with the most amount of info about it. Even just knowing would be great, but more info would help in solving.

I’ve disabled all forms of caching and my host tells me they’ve done the same. Memcache is enabled for PHP but not configured for WordPress, but I don’t think this is a problem right?