Geopak Drainage Error Computing output for a network with Pipe-Arch

I am trying to design a storm drain network in an area with limited cover. When I try to use the "Pipe-Arch" option, Geopak reports an error. The same network runs just fine when using circular pipe or box culvert or elliptical pipe.

I checked the drainage library, and I didn't find any glaring omissions or errors in the "Pipe-Arch" dimensions.  I am uploading the drainage file and the library to the secure folder .

The drainage network in question is OUT489N, and the issues are with pipes P-IN485N, and P-IN489N.

Any help in troubleshooting this error is appreciated. Thanks,

Vinod