Tab Targeting.

[Bixby]

Is this a keyboard problem?

Yes. The gamepad controls, especially if you're good at facing your character and/or camera beforehand, are much more predictable and intuitive.

Tab works fairly predictably a good deal of the time (left to right). Unfortunately, that's not a terribly useful way to cycle targets in a lot of situations, and the predictability goes out the window often enough that in order to use Tab effectively, you basically have to do camera gymnastics.