I've attached screen caps from both versions so you can see what I'm seeing.
The seems to be a different if face numbering. In both examples I started with a blank project and added a cube. In the v100 images you can see that I'm able to hover over and select one of the side faces; in v100 that face is #1.
In v151 that same face is #4. You can see from the two v151 images that the topmost face can be correctly identified and selected. Hovering over other faces seems to identify them correctly, but clicking on any face selects face #0 (topmost).
Edit: the attachment quota allows me only one file -- so I'm attaching the v151 that shows the mouse hovering over face #4 (side, viewer right) but with face #0 highlighted.
The seems to be a different if face numbering. In both examples I started with a blank project and added a cube. In the v100 images you can see that I'm able to hover over and select one of the side faces; in v100 that face is #1.
In v151 that same face is #4. You can see from the two v151 images that the topmost face can be correctly identified and selected. Hovering over other faces seems to identify them correctly, but clicking on any face selects face #0 (topmost).
Edit: the attachment quota allows me only one file -- so I'm attaching the v151 that shows the mouse hovering over face #4 (side, viewer right) but with face #0 highlighted.