How do I separate the AE and AF locks in camera Pro mode?

[ostrogothic]

This is driving me nuts. When I'm in pro mode using the S7 Edge main camera, I can call up the AE and AF lock circles by pressing and holding. They separate briefly, then come together into a single circle. Sometimes I can drag one away from the other; sometimes I can't. Is there some reliable way to do this? (Basically, I want to lock AF on one point, and AE on another point.)