Hard to add control points like this. 
([Play Raw] St Monans Breakwater, Fife Scotland raw exported from PhotoFlow.)
Hugin
GIMP 
I’m not sure that hugin supports your crazy linear color space 
Yet it is mad when I open a file without a colour profile. 
Maybe Hugin does not understand V4 ICC profiles…
Have you tried setting the 16/32bit preview to linear or gamma corrected? Yours looks like it’s still the default, logarithmic.
I’ve noticed that the preview aren’t colour managed, or if they are, the management is way off and done with very low bit depth, as 32bit images oftentimes will clip large portions of the image to pure black…
@afre have you tested v2 vs v4 profiles, identified the source of the problem or found a solution? Which version of Hugin have you tested?
Sorry @Morgan_Hardwood, I haven’t pursued this matter. I remember someone else mentioning this or a similar issue in another thread, so it is worth following up.