I'm having trouble displaying an aerial imager in the HEC-RAS geometric view in version 5.0.1. I've added the aerial, a project TIF file, to the RAS Mapper and it shows up without issue. When I go to the geometric view and select "select layers to view in background" and select the imagery, nothing shows up. I'm in a blank geometry file without any data created yet. I've tried doing View > Set Geometry Extents, but that still leaves with with white space.
I think that you have to export the terrain layer as an image by a right-click and choose export as map, then you add the new file exported as a map layer.