There is a bug that causes them to often be unstealthed for no reason at all. It’s a recurring bug, but seems worse in DF. I’m not playing my rogue because of it.
Also, the assassination two piece set bonus makes it so you can’t restealth if you have rupture ticking on someone. Imagine that. A tier set bonus that actually makes your class unplayable. And, having it be that way for months. Not sure if it is fixed now.
Just checked. Not fixed. Broken since MAY.