32-bit floating point image data incorrectly represented as elevation data

Pix4Dmapper exports reflectance datasets derived from a MicaSense RedEdge camera in individual bands as 32-bit floating point raster geotiffs.  It'd simplify my workflow if I could combine these input files and export the result as multiband geotiffs using GlobalMapper v19.1.

I've been struggling to convince GlobalMapper that my input data are image data, not elevation data.  Is it possible to somehow force GlobalMapper to treat input data as image datasets, rather than assume that they represent elevations?

The reason why I think this is a problem is because when I head over to Export->Export Raster/Image Format->GeoTIFF->Multi-band file type->"Set Up Band for Export"... I'm given a list of three input bands to choose from... red, green, and blue.  The input datasets consist of a single band, so I'm not sure why & how these extra bands are being generated.