6.5.1.3 installed and no issues here.
Good news all, at least for those with a Windows server that are having the slash issue, this seems to be resolved now with the public release of 6.5.1.2.
Not sure if it’s appropriate but I saw another thread where support@theeventscalendarsupport.zendesk.com was used for a support request, so I sent it there.
Request #: 607318
It is definitely related to a Windows server, at least for my example. This is not a public web facing instance and it used for internal usage only.
I do not have a paid license so I am unable to open a support ticket.
I can email you if you want to share your email address.