Non standard hub bearing?
Sounds like the bearing has the wrong dust shield.  Sizing lines up closer to an imperial(inches) sizing, 1/2"x1 1/8" x 3/8"ish.  The inside and outside diameters are close, the width is less important than the ID and OD as you typically have a preload adjustment on the axle.  Try a 1616-2RS (9.5mm wide) or a R8-2RS (8mm) bearing.

Alternatively, If the bearing is simply feeling rough, you can remove the dust cover with a knife, clean out the bearing with alcohol and repack with a marine grade grease.  This may improve the smoothness if the races are not too pitted/corroded and add a bit more life to the bearing.