All the time

Happens to me WAY to often.

have a coworker like this, great guy, but talks way too softly

In my case, it would be around 7-8 times until the person thinks I'm making fun of them and they storm off

Then you realize they asked you a question.

All the time. Like today at work when that happened 8 times

Smile, nod and hope it wasn't a question

Once I went on to say "what" 5times in a row and still didn't know what the person said :D