Most Helpful Girl
We could sit and make up our own conclusions but you will never know unless you ask her. Yes it is weird, honestly I have no idea why someone would change like that. You could reach out for her and tell her that you want to see her and this was strange. I mean it's not fair of her to do this.. or you could wait until she contacts you, keep yourself busy meanwhile.
Most Helpful Guy
I think it has more to do with her having mixed feelings and maybe she's afraid of falling back in love after having broken up with you. Not sure why the two of you split, but maybe she's apprehensive about those reasons returning and is afraid of getting hurt.
Like an anonymous poster said, you can ask her if she's uncomfortable hanging out as friends, or maybe, since you've already tried communicating with her, just step back and allow her to contact you, so you two can talk when she's ready.