After Roblox was completely spotty the other day, I started experiencing this same issue the same day afterward. I thoroughly went through my entire system to clear any trace of Roblox’s existence on it and it still gives me this issue, which means this is not anything Cache related on the system.

You could say the Cookies are the issue, but that wouldn’t be the case when just trying to log in via the Roblox app. When trying to do so, it just gives the same error as OP and Quick Login and all of that stuff does not function either. The client acknowledges it receives a request and it asks me to confirm the code on the other device, but upon accepting it just disappears and leaves me at the login screen.

I thought using Bloxstrap had something to do with it, and when I went to try just regular roblox I was met with the same exact issue. Roblox is completely inaccessible for me.