Map creation - exporting PNG for import into FC

[Zumwalt_446]

I am creating a test map in qGIS and attempting to import it into the FC map editor. My terrain import into qGIS is done using a GeoTIFF file for the area of interest; I then change the style for that layer to use a singleband pseudocolor style with several elevation bins. I can see from the layer display in qGIS that the elevation is being correctly processed and has the correct color applied based on the style specification.

However, when I export this as a PNG and then import the PNG into the Map Editor, portions of the map show as "Elevation Unknown" in the map scan. Are there additional steps required beyond what I have described above?

The PNG I am using is attached for reference.