Transformation Rules - Possible Bug

I have an issue, since we migrated to V9, OS is adding on its own a space after transforming a member and this prevent us from loading the data to the member. (This is in the validation step when it fails)

• Data source has been checked, adjusted, and tested in many ways. The extra space doesn't come from here.
• Transformation rules have also been tested in many ways, and the space is also not here, we event tried one-to-one, masks, all ,and this is not the issue

The error is only happening with 2 UD3 members US4 & CA4 both ending in 4, I created a fake one for testing "US41" and this one works fine. I have been checking with OS support, but they just want to repeat over and over the same testing we already did with them on a call

To me, after checking all that I could, seems like a bug in the new V9.1, but if anyone has any ideas please let me know.