Rounding error? Have you received bitcoins from the faucet, then paid 0.0495 btc to someone. Ever done anything in the 3rd decimal or beyond? I have 0.01 at TAABL that I can’t withdraw due to rounding error. Still, +50.00 is +50.00, and should be able to withdraw that.
Fresh blocks take something like 100 blocks to confirm. I assume you waited.