After ProBuilder 4.0.4 on MacOS, it is impossible to select a face, edge, or vertex by clicking. STEPS TO REPRODUCE: 1. Create a blank project on any Unity version on MacOS. 2. Install ProBuilder (any version from 4.0.4 onward) from the Package Manager. 3. Create an object such as a cube, attempt to select a face, edge, or vertex. 4. The attempted selection will highlight on mouse-over, but upon clicking, it will blink as if it was selected and deselected instantly. A workaround is to select using a box selector, but sometimes that picks up a backface or an adjacent part. Any version before 4.0.4 works just fine.