same for me with your file. But my 32-bit dng files (converted from tiff) of Photomatix work correctly. I can not find an error in the dng file, but I am not an expert of this file format...
Workaround: You can add an gradulated filter with +4 ev. to to right side of your image - outside the image plane on the gray lightroom background. This will ajust the exposure by +4 for the whole image. You can repeat this process, if needed.
Thanks for taking a look at this.
I think that converting 32bit tiff files to dng only changes the wrapping. So in a way it's understandable that they are opened in 32bit mode. I still don't understand why normal 32bit dng files can't.
Thanks for the top about the GND filter. I thought about using a brush all over the frame, but a GND can also be used. I suspect that if LR opens my dng file in 16bit mode than it uses a narrower pipeline for the tone curve and color manipulation so the result will be inferior compared to a 32bit tiff file (developed with the same settings). That's why I'm trying to find a way to open the dng files directly in 32bit mode.
Does anyone have any idea?