Hey Andrew,
Thanks for reaching out to us!
This is definitely a strange issue to be having. As an initial step, have you tried following our Testing for Conflicts procedures to see if there is an issue with an existing plugin or your active theme that is causing the problem? Additionally, have you checked the date format settings under Event Settings > Display tab (https://cloudup.com/cybUQkEW9qj) to ensure that there aren’t any formats added there that might cause this specific output?
Let me know if this helps.
Thanks!