Aimee Eccles as McIntosh's Apache wife. Why was her face always hidden?

Aimee Eccles, a pretty Eurasian actress, was in this film and also in the 1970 Western, Little Big Man, where she played Dustin Hoffman (as Jack Crabb's) Cheyenne wife.

In Little Big Man, you could see her face very clearly, but in Ulzana's Raid, she is first seen through a blurry glass window, then in longshot, and then in several shots with a blanket obscuring the lower half of her face. It seems like Aldrich was deliberately trying to hide her, which was a shame, because she was quite attractive.

She didn't get any dialogue in Ulzana's Raid, but she spoke quite a few lines in Little Big Man. I wonder why her face was hidden in Ulzana's Raid? Perhaps she had a skin condition at the time, or had recently had cosmetic surgery or an accident?