What are the possible causes of a faculty position not being filled? I applied for a tenure-track faculty position at a particular institution in the U.S. I was selected for a skype interview, but was not invited for an on-campus visit. I snooped around on the department seminar web page, but did not find any evidence that this particular department actually ever invited anybody for an on-campus interview.

Today, I received an email from the department stating:


  Thank you for your interest in the faculty position within the Electrical and Computer Engineering Department at the University of [redacted]. Our search to fill this position produced many impressive applicants. However, for a number of reasons beyond the department’s control, the position was not filled. 


I can think of a couple of reasons that a department may not fill a vacancy, such as:


the finalists all ended up taking a job somewhere else
none of the finalists could agree to the terms offered by the department


So, besides those possibilities listed above, what are the other possible causes of a faculty position going unfilled?
You will probably never know the full reason, because departments are not quick to air their internal issues with job candidates. But here are a few possible reasons:


The search was halted by higher administration. One possible reason to do this so late in the process is because of funding changes (e.g. the funding for the position disappeared or was reallocated elsewhere). 
The search was halted by the HR department due to some violation of hiring practices. 
The search committee was unable to come to an agreement about who to bring to campus for an interview, or the dean rejected all the candidates before they were interviewed. 
Although this is less likely, someone who had planned to retire might have decided not to retire, or someone from another department may have been moved into the department (e.g. for legal reasons to settle a complaint).