The top center needs 90° rotation. Algorithm: Then rotate cube and repeat.
(R U R' U') (M' U R U' r') (Where r = R + M) fisher cube algorithms pdf
An edge piece might appear flipped because its two colors are on opposite sides of the cube, but it is actually correctly oriented. Standard edge-flip algorithms (like R U R' U' repeated) will destroy the cube. The top center needs 90° rotation