I think that in some cases, intentional ignoring may be one of the more subtle things we might not have picked up on (much less know WHY, esp. pre-diagnosis or having heard of ASD) - I can tell you in the past, when I was in my early 20s at uni/college (back in the '90s), I had it happen more than just coincidentally, I knew that it was something to do with ME, but couldn't put my finger on it (other than being "different") - and neither could the therapists I saw - they just "gaslighted" me by saying that they might have been busy or not noticed me.
Turns out, Aspie intuition is better than we think it is at times!!
This further confounded me, when I got feedback that *I* was apparently the rude one, yet I can barely recall any instances of ME intentionally ignoring people...I'd have the odd moment of "face blindness", which was kind of embarrassing, but was 100% unintentional.
Mostly this happened with females (big surprise, sarcasm) which I guess is a visceral response to a male who doesn't appear "natural", yet of course narcissists and other cluster B personality disorders completely bypassed her radar.
One time I asked a girl directly "You seem to be ignoring me, why?" and she replied, "Because you're a weirdo."
YIKES...
I didn't "poll" people in this manner, but my guess is that had I called more people out on intentionally ignoring me, the most common response would be denial, e.g. "I didn't mean to ignore you - I just didn't see you."
Other times, when it was a group avoidance maneuver, where they all got into their "hive mind mode", I could detect their darting glances and shocked expressions, and head tilt to "c'mon, let's go this way, where he won't pester us"... again it's uncanny how I can pick up non-verbals when people are trying to avoid me, but not proactively to prevent that sort of behaviour in the first place!! ![/b] In hindsight, it was clearly due to some manifestation that put them off in the past, e.g. abrupt change of topic or failure to keep on current topic, glazed confused expression or improper expression when a nuance was misinterpreted, innocently asked to clarify a nuance with a sexual connotation, or 'd' all of the friggin' above...
Oh and don't even get me started on this one time, at age 21, I went on a date with some girl who brought along her two friends (in hindsight I shoulda been the "alpha male" and said screw this and walked out), and they just chit-chatted amongst themselves, barely involving me at all.
And as you might have guessed already, there was more than a couple of times I can recall when I approached someone and she (usually a she) said to me, "Oh! I'm...actually kind of in a hurry, gotta go, sorry!!" but I could tell she didn't look that rushed before she saw me, and I could tell she likely saw me in her peripherals or a side-glance, not directly (as did the others who ignored me).
So, yeah. I guess during my 18-23 demographic experience, one could have said that "ignoring is the new name-calling."
(e.g. they were non-verbally calling me a weirdo, loser, freak, nutcase, etc.)
Maybe in those institutions of higher learning, there ought to be more sensitivity training about those on the spectrum, just like they have for minorities and LGBTQ. But something tells me that's going to be quite a struggle... at almost 50 now, I sure hope to see that in my lifetime!! !