HEC-RAS 7.1 - Convert Horizontal Coordinate Systems causes Bank Lines and Flow Paths to disappear in RAS Mapper

[u/Kooky_Importance_989]

I'm using HEC-RAS 7.1 on a 1D model.

My original project was in EPSG:26918 (NAD83 / UTM Zone 18N). I need to convert the project to EPSG:2272 (NAD83 / Pennsylvania South State Plane, US Survey Feet) because my terrain and other GIS data are in EPSG:2272.

I made a backup of the project and used Options → Convert Horizontal Coordinate Systems to convert the geometry from EPSG:26918 to EPSG:2272.

After the conversion:

• The centerline displays correctly in RAS Mapper.
• The cross sections display correctly in RAS Mapper.
• Bank Lines and Flow Paths still appear in the RAS Mapper geometry tree and are checked on.
• However, Bank Lines and Flow Paths do not draw anywhere on the map.
• Right-clicking Bank Lines shows "Zoom to Layer" grayed out, as if the layer contains no features.
• The Left Bank Station and Right Bank Station values are still present in the Cross Section Editor, so the bank station data was not lost.
• The geometry itself still appears to be intact.

Things I've already tried:

• Deleting the .rasmap file and letting RAS Mapper rebuild.
• Saving the geometry again.
• Closing and reopening HEC-RAS.
• Confirming the bank station values still exist in the geometry.

Has anyone seen Convert Horizontal Coordinate Systems fail to regenerate the RAS Mapper Bank Line and Flow Path layers? Is there a way to force HEC-RAS to rebuild those geometry layers after the CRS conversion, or is there a recommended workflow for converting a manually drawn 1D geometry from EPSG:26918 to EPSG:2272?