Renderview does not display EXR float32

[Macbeth R.]

Using arnold and maya, with the renderview set as 32bit float (HDR), if I use IPR and set for example the Z pass to be the display pass in renderview, I am able to control the exposore from the viewColorManager node,

however If I load the same exr of the Z pass with openfile from renderview, nothing is displayed only black color, I try to save the pass as float tif 32 bit, and at least I get and error in the console saying only 16 and 8 tif are supported.

How can be that the IPR works in 32 with the z pass, but not loading a external exr? I try to find the ipr tmp image, for the ipr and is not float.. My guess is IPR (z float) is only stored in arnold frame buffer.

Is there any plugin for maya that can make renderview support 32 float exrs??

Any other ideas?  thanks!