macOS High Sierra 10.13.6
MacBook Pro (Retina, 15-inch, Mid 2015)
2.5 GHz Intel Core i7
16 GB 1600 MHz DDR3
AMD Radeon R9 M370X 2048 MB
Intel Iris Pro 1536 M
blender 2.80 alpha 2
When trying to snap vertex to a mesh and retopologize it.
editing in wireframe mode.
I am clicking the snap button (magnet), it works fine, BUT when changing it to a different mode FACE, EDGE AND VOLUME. clicking the vertices is very difficult. some of them i am unable to click at all and some of them are chosen when i offset the mouse position and then click.
clicking out of edit mode and back in seems to fix the issue.
also, it looks like it happens only on the first time you are in edit mode, after exiting and entering again it won't give you any problems, so sorry that attaching a file is not possible.