3D model exported from Maya behaving weirdly

I have some 3-4 3D character models which are claimed to be exported with the same configuration from Maya by the 3d designers. Now, some of the models(animations) is working fine in Humanoid settings and not working in Generic mode and vice versa. The one which is working in Humanoid seems to have only one of its feet as crooked up. Though in maya, everything seems to work perfectly fine.

Now if there was some issue with the configurations while exporting, then it has to affect both its feet and not just one. I have also checked the T-Pose and automap settings in the Unity and everything seems to be fine.

Suppose for character A, all the animations work with Humanoid settings, then in Generic, for all animations it is kind of idle in a T-pose structure and do nothing not even simple walk animation.

I have been using Unity v5.0.1.

Please, if anyone could come up with any help would be highly appreciated.