Welcome to Coldstone!!!

Friday night something happened that simply did not make sense to me. I'm just going to present the facts of this situation and let you provide any justification or excuses you like.

So my bf decides he'd like some Cold Stone ice cream a little after 10 p.m. We head to Cold Stone (/Tim Horton's) and go straight to the counter where you're supposed to order. There's a young lady behind the counter, mixing up some ice cream. She doesn't look up, doesn't say hi, I'll be with you in a moment - none of that. Then she turns around, goes to a table and fiddles with some stuff there. At this point I've decided that I'd like to taste a new flavor they have this month, and I'm hoping that soon she'll ask how she can help us.
No such luck. After a few minutes, she goes to the drive-thru window and passes some items outside. We're like, OK, she's done with them, maybe she'll come help us now.
Nope. She returns to the counter. Right in front of us. And starts cleaning up. She's scraping the table, head down, like we're not there, so my bf says (not in a loud tone, mind you) "You in a bad mood or something?"

She says,"huh?" Doesn't even look up. And keeps cleaning. At this point, I'm upset, I look at the bf and go, "Wowwww. Do you really still want ice cream from here?"
He says nothing. And then the lady turns her back to us, walks over to another table and starts cleaning over there and fiddling with some spoons. That's when it became clear to me that we weren't going to get any ice cream that night, and I left.

Ladies and gentlemen, there were several people in store with ice cream, which means she'd helped them not too long before. He and I were the only people in line, and he's very tall. So I know she saw us. And we stood there for at least 15 minutes - ample time to be acknowledged.

I really can't figure this one out. We both went to the car and sat there, stunned for a moment.

I've worked in retail. There've been times I had to straighten, answer phones, operate the register and help customers. I understand multitasking. But I was always taught to acknowledge a person in front of me. And I was NEVER taught that a potential customer should have to flag me down or beg me to assist them - so please don't ask why we didn't speak first. That's not our job. That's hers.