Subconsciously I will ignore you, sometimes on purpose.
The human brain on a normal day will consume 20% of your total energy just keeping you alive.
Any extra to that can feel exhausting so by design, it must conserve energy by disregarding the majority of what it is exposed to on any given day.
So if you are any of the following I will quietly move on;
Boring, irrelevant, too late, too early, too complicated, too risky, too slow, too fast, untrustworthy … you get the picture.
Getting someones attention is hard enough, be purposeful in your communication to keep it.