Why is there...such a difference between how people interpret the use of ellipsis's when communicating...

This might be the funnest question I've ever seen on Taro, kudos.

For the "Hey...how's it going", I'm envisioning someone sad.

For "Great job...", I'm envisioning someone being sarcastic or half-hearted.

I think it's because ... translates to a very long pause in real-life and you generally don't do that unless there's a negative emotion.

For many engineers, English is not their first language.

My general rule is to avoid the potential for misinterpretation unless I know the message recipient. Ellipses fall into this category -- just stay away!

Haha, the ellipsis can make the word feel like it's drawn out like a depressed sigh. I found a video of Eeyore (the sad donkey in Winnie the Pooh) that shows how people might interpret the ellipsis:

https://www.youtube.com/watch?v=CQI0E1WCLMU

From my anecdotal research and strictly comparing native English speakers it nearly always occurs in people over a certain age demographic.

I asked my mum and a mentor at work the same thing as they had a tendency to do it. (Age 40-50s)

But from their perspective it was used to convey a line break or just an alternative to having one full stop…

I thought about this awhile back but the topic came back to me after starting to watch Alex’s course on communication.