Hmm...That is very interesting! I have problems (steps, posture...) dancing with a few fellow students in my AT class, while doing fine with others or with my teacher.... is that the same partners I have incredibly good connection with in the other dances is simply not translating over to tango...
I always assume the problems are mine since everyone in the class have had AT lessons longer than me. It turned out that they (and they get corrected a lot by my teachers) are experienced ballroom dancers but have not yet adjusted to AT.
Not saying that this is the case with your dance partners, just an observation from a beginning student. Have you asked your teacher(s) about these things?