Hey there, Communicatio!
Sorry for the trouble with Month View here. I do see what you mean, so let’s see if we can figure this out together. 🙂
First off, I see you noted trying:
Deactivated all other plugins? Yes
Switched to a default theme? Yes
Did you happen to notice a difference in those conditions? How about when deactivating all other plugins and switching to a default WordPress theme (like Twenty Fifteen) together?
There also appears to be a lot of caching on the site. If you’re using an caching plugins (or your theme or host uses it), please be sure to clear that out when following these troubleshooting steps because that can have an impact on the testing as well.
Let’s start there and see what we find. 🙂
Cheers!
Geoff