i think the gray dot just gets hidden? it randomizes its placement - and sometimes that placement can be hidden within the gray values of the image beneath it. I could be wrong though! either way, I think that part needs some tweaking because its either far too easy (right next to it) or far too hard (literally impossibly far). its a hard balancing act! but if you keep running into it - lemme know and ill try to troubleshoot it for ya.
Huh! Im so sorry that's happening - although, unfortunately, I cannot recreate it so Im not entirely sure how to fix it. The best option i can think of it is sadly to restart the test from the beginning (sorry!). The most recent patch has a "reset test" option in the main menu for restarting to the beginning. I wish i had an option that fixed your current game though - so again, apologies! if that *doesnt* fix it, definitely let me know!