Emails from no-reply@roblox.com have stopped arriving

I have 2-step email verification for Roblox using my comcast.net account.

It had worked a few times prior where I would tell the Roblox website or app to send a verification code to my Comcast account, but now it is no longer arriving, so I am unable to access Roblox at all. 

I have tried this from the Roblox app, different browsers and nothing works. 

It is not in my Spam folder. Roblox support claims innocence. Is no-reply@roblox.com being blocked?