PAB - Error

I am reaching out to the community to see if anyone is running into the issue I am experiencing. Our PAB stopped working on Tuesday. The only known major change organization wide was the December Microsoft Patch Tuesday. The error we are getting is "ADD-IN ERROR: Sorry, you seem to have lost your network and/or Internet connection. Click "Retry" once you're back online."

I've reached out to support but no solution yet. Support provided, "Can you make sure that the PCs in question can reach https:// training.knowbe4.com/api/v1/phishalert/ (allow outbound connections to remote servers on port 443, that is the server URL Phish Alert is trying to contact)? The URL above is an API callback and generates an error when the URL is popped into a browser, this isn't proof of a connection. Please make sure this URL isn't blocked through any proxies/firewalls."

The machines that I've tested the URL on, we cannot reach that URL, but the same happens when I try to reach that URL on my phone and laptop that is not connected to our organizations network. I even tried reaching that URL from home, but I am still getting a 500 error. We are also not blocking any outbound connections on port 443, but we have whitelisted that URL for the sake of this issue. That didn't resolve our issue. 

Again, the PAB was working fine up until the patch was deployed organization wide. I am thinking the patch could've had an impact on this. I need to know if anyone is experiencing this issue after they've applied December's patch? Or if anyone knows why and how we can get this resolved. Thank you.