Ok, I found where is the problem. Since Maya 2016, Autodesk remove section High Dynamic Range Image Preview Options
and hide attribute Float to Fixed Point
(in mel, attribute is hdrMapping
). However attribute is still present and set to value 0 (clamp), so we use it by this way. So, for now, you can set this attribute to 1 by mel (where file1 is name of file texture node with hdri map:
setAttr file1.hdrMapping 1
After that, you must rebuild cache for your dome light (in dome light shape, cache section -> rebuild cache).
We will discuss it and we prepare some fix for this issue.