I found the cause. ImagineSim KATL (Hartsfield-Jackson Atlanta) scenery was installed. With that scenery installed, switching the CRJ EFB from KMGM charts to KATL and selecting a KATL chart causes the complete CRJ WASM failure. I removed the ImagineSim KATL scenery, restarted MSFS, repeated the same test, and KATL charts now load and display normally with no WASM failure. So there appears to be a specific conflict between the ImagineSim KATL airport data and the CRJ/Navigraph integration.