With these stories, it is usually pretty obvious to me what the person did wrong. It is not always clear that they should have been denied, but it is often clear why they were denied (and my sympathy is therefore tempered).

In this case, the lack of details makes it hard to say. However, as you pointed out, she mentioned a "visa technicality."

She also says, "I further explained that my current work visa application had been complicated due to a filing mistake and that I had been waiting on a decision."

Generally, if you leave the country with an application outstanding, that application is considered abandoned. So, if I had to guess, it looks like she was attempting to enter the U.S. to live and work without a visa. Anybody surprised at the result?