I have just noticed a strangeness in LR and PS: I have the latest builds.
In 16 bit mode, both LR and PS dehaze tools seem to work as I expect.
In 32 bit mode, ie after using LR HDR Merge, the LR dehaze only seems to have an effect with negative dehaze.
That is moving the dehaze slider to the right doesn't seem to change the image.
I'm on Win 10 and using a Geoforce 750M graphics card.
Has anyone else noticed this? Or is it me :-(
Canon 5D IV Raw Files
Using Win 10, Lightroom Classic CC 7.1 on a DNG created from a Lightroom>Photomerge>HDR, Dehaze functions in both directions.
Edit In Photoshop 19.1.0 - Open as Smart Object - Invoke ACR - Dehaze functions in both directions.
I am not sure what you are speaking about with regard to 32 Bit. Lightroom Merges are 16 Bit - Floating Point - see: https://protogtech.com/adobe-lightroom/adobe-dng-hdr-format/