I assume she is an adult or at the very least is out of high school so it’s very unlikely she is jealous of anybody or has a crush (one can think someone is cute and nice without it being a crush). Crushes and being jealous of other girls is common for high school students, not adults.

There’s no way to know why she’s not interested in talking. There doesn’t really have to be an explanation or a reason. I’d not worry about it. I’d focus on my work tasks. You spoke to her a few times. It’s not like meaningful friendship abruptly ended. You are strangers