If you are still having your keystore and then you can also try to use MEW cx to claim your UNI. As far as i know, if it's not the only metamask that makes the users able to claim their UNI coin. I have been trying to trigger the claiming process through MEW CX and it looks like it has the same mechanism with the metamask but you will able to sign in your wallet use more ways.

I hope you can try to take a look at it.