I always start by choosing the ratio, so I ran into this fairly quickly.
There’s other odd behaviour as well:
The inverted orientation doesn’t happen the second time you enter the crop tool: Crop Tool -> 5:7 -> Reset -> Close -> Crop Tool -> 5:7 does give the expected orientation, but the frame isn’t centered on the image the way it is with the first selection. This is true of any aspect ratio in fact.
Say we started with a 3:2 image in landscape orientation above. Now choose Original and you get a 3:2 frame that extends beyond the bounds of the image, to the left.
Now choose Unconstrained, and you get a 5:7 frame flush left of the image. (Also not dependent on the first crop being 5:7 it seems; similar for 4:3, etc.)
It does seem to behave better if you redraw or move the crop frame before choosing a ratio, but it should be well-behaved either way.
The behaviour of the pointer is also unpredictable. Sometimes I’ll enter Crop Tool and get crosshairs to redraw the frame, other times I’ll get a hand to move it. When I get crosshairs, sometimes I can click outside the image to get the hand, other times not. I haven’t really figured out if there’s any pattern to this, but I’ve accidentally redrawn a frame when I expected to move it a number of times.
Or Reset any crop choice and you’re presented with a frame in the original aspect ratio, which is reflected in the drop-down. Now chose Close and you don’t get the indicated crop, you get the unconstrained image, as if Unconstrained had been chosen before Close.
Most of these were present in PL2 as well, maybe even PL1. (Think I reported the last one on PL1.) If there’s a logic to it, I have yet to discover it. 
Edit: I take it back about being better behaved if you start by moving/resizing: it’s still flaky. For example, resize a 3:2 Original crop by moving the upper-left corner inwards, then select 4:3 and it’s still reasonable, but then select Original or Unconstrained and the fun begins in a similar fashion to my previous cases.