Unlimited PTO appears to be a bone of contention here. The simple fact is that "unlimited" PTO is never unlimited in practice, and there's the all-important caveat of "subject to management approval" even with unlimited PTO. Unlimited PTO is simply a way for the company to get away with no money paid out to you at separation from the company. In that sense, it really is a scam that can entrap the unwary and the naive.

The other fact of life is that HR is there to protect the company, not the individual employee, when there is a problem. The priority for HR is to eliminate, reduce or limit company exposure to liability from noncompliance with employment law. A secondary objective is to be the eyes and ears of the company (via exit interviews, complaints from disgruntled employees, etc.). As with any job function, HR can also fail at this task (the Susan Rigetti case at Uber), sometimes in spectacular ways. If you are in an adversarial situation with the company, be very careful about HR and document every single dealing with them. Seek independent legal counsel, and walk away from a bad employment situation before you even need to seek out such support.