I'm trying to access the Online Lobby in the Poke Center but it says.....

[PhantomUnderYourDesk]

I tried typing what you said in the search bar but it didn't find anything.

Does simply typing 'Uranium' not lead you to the Game? Weird.

I'd try to re-install the Game via the link in the side bar on Uranium's official Reddit, it's the latest version and already patched. That has already solved several problems, and it does NOT affect the savefile as that's usually located somewherelse. (If you want to be safe however, backing it up is never wrong. It's the RXDATA-file.)