"Unlimited PTO" is a policy ripe for employer exploitation. In practice at my workplace, this means a) Cannot take more than 2 weeks of PTO at a time (even if you want to go unpaid). Automatic manager rejection. b) Cannot be combined with other forms of time off. I had a kid recently and was told that PTO cannot be combined with FMLA. c) When I told them that I wanted to take FMLA, I was told by the Dir. of Engg that I could not take any further PTO for the rest of the year even with the "Unlimited PTO" option and said policy was unrelated to FMLA. He went so far as to state that when he worked at Twitter, there were folks who would alternate working 2 weeks with 2-week PTOs cause of the Twitter's "Unlimited PTO" policy. I found that extremely insulting and de-motivating.

Of course, I am sure a lot of this has to do with management culture /values. Another colleague in a different department is being discouraged from taking FMLA (which is borderline illegal). However, he feels stuck as the company is doing his Green card application and has him by the balls.

All that to say, I took my FMLA and handed in my notice as soon as I returned.