I read through this entire thread and it seems very weird that violet ultramarine would act this way. I wonder if WSP sent the wrong product by mistake. Ultramarines are normally very stable in CP. At worst, if your base oils are yellowish, it would shift more towards a grayish purple. But not brown, especially if no fragrance were involved.
You should be aware, and this came up in another thread, that sometimes colors will morph initially in the soaping process but will settle down once saponification is complete. However, if the color is new to you, it's best to test it in a small quantity of soap batter first.
I'm glad you got the result you wanted in the end.