I’ve found that some african airports are not part of the ATR database and flight plans that include them are not loaded correctly.
For instance, you can create a flight plan in Simbrief from HKJK to FWKA, and the latter airport is not recognised, so the FP is only loaded with DEP/ARR and nothing more. The enroute waypoints are not loaded. Also, FWKA cannot be used as a waypoint in any other FP. This plan can be loaded in other airplanes, for instance a Citation.
A plan created from HKJK to HTZA, for instance, is loaded correctly with all its waypoints.
Besides FWKA I have found some more airports that are not included in ATR’s database, all of them near Kenya, Tanzania, Uganda, Malawi and that area. All those airports appear normally in tools like Simbrief or Little NavMap and are usable in other planes.