I've been successfully using RiverGIS for mesh creation, but if a mesh includes too many cells the HEC-RAS Geometry import fails. I'm not sure where the threshold is, but it definitely does not work at around 250,000 cells. This is a problem for me, as I often work with large 2D models.
What happens is that the cells that were created along the breaklines are absent. Here's an example screenshot where the regular grid imported, but the curvilinear portion within the channel fails.

Anyone else notice this issue? What is going on here?
FYI, I cross-posted this issue to github: https://github.com/erpas/rgis/issues/28
Thanks,
-Matt