I think it is always like this with mentorship program. As a professor, I volunteer to be a mentor to new grad students all the time and only a handful of them take the time or put in the effort. Often I get one email and then nothing. I try to be understanding. People are busy, things happen, etc. But it can be annoying. I've thought about signing up to be a mentee but my situation is so different and specific I really am not sure anyone could be of any help.