Solidworks split the Arc surface when export as step file

Hi, everybody.

I am in trouble when I export solidworks model as Step file. Cause when I import this step file again, a whole Arc surface is split into two parts which is different from source model. However, I don't come across this case when I use Autodesk Fusion360 software. So, could some one explain it. Should I set some configurations or do some others? The specific case is as follows.