NIF rotation matrices including scales are not supported
http://www.nexusmods.com/morrowind/mods/42406
I'm using this mod which replaces a few meshes. One of them is ex_redoran_steps_02. While wandering around Ald-Ruhn I noticed that the normal maps are inverted for the side walls in this model. I started up original MW and it looks like it is supposed to. It looks right in NifSkope as well. This problem seems to be specific to OpenMW.
(RM-2052 from redmine: created on 2014-10-24 by no name, , closed on 2015-06-30 by nobody, relates #2168 (closed))