What you were expecting to happen, and what actually happened?
I took an old lineup, cleared it, made a new one, and then gave one of the troops a trait. The old lineup then reappeared, superseding the new one in its slot (which was not meant to happen I assume).
What are the steps to make it happen again?
Do you have any screenshots or video you want to share with us so we can see the problem? Attach them to your post!
Screenshots not relevant.