I have yet to meet a submissive (male or female) that I can't top (and I was a "whore" in my twenties). Topping from the bottom is a manipulation power struggle technique, simple as that. The question is not if she can be topped, but whether the dom considers said submissive worthy to him of the time needed to break her out of that habit. All submissives test their doms, it is up to me how far I let her take it, before "yanking the chain" and showing her that she was allowed to get away with stuff only for my own amusement.
The difference between communication issues and topping from the bottom is honesty of the submissive in her communication and sincerity of her submission, at the least that means trying or wanting to submit. It can also happen in cases where a "sub" is better suited to a different role and with those who get lost in it, while their need isn't submission but kinky sex.