I found almost no discussions of this among philosophers, not surprisingly.
Not surprisingly because there are so many thousands of articles and books on free will that it's hard sort through them, or not surprisingly because you found that philosophers (as you expected) did not discuss the phenomenology of free will in those many thousands of articles and books?
In my experience, it is almost impossible to find any (not obviously false) idea that hasn't been pretty throughly discussed at some point. One of the greatest things about, say, the idea of FAI is that friendliness as a formal decision procedure is a genuinely new idea. That's extremely, fantastically hard to do. I expect the problem isn't going to be finding philosophers who discuss this very question, but sorting through the mountain of such discussion for anything good or interesting.
Philpapers has a pretty okay search engine. I found this article by John Searle searching for 'free will phenomenology'. I didn't read it, but the abstract leads me to believe it has some discussion of the phenomenology of free will.
Uh, sorry, I should have phrased it differently. What I meant was not just that this angle is probably not very popular, but also that it is hard to find, given that the specific language philosophers would use would be unfamiliar and non-obvious to someone outside the field. Additionally, it would be a topic more likely to be studied in neuroscience, psychology or even psychiatry than in philosophy of mind. Routine paywalling doesn't help, either. But yes, I also admit to a certain prejudice against a discipline which has multiple warring schools arguing ...
Given the spike in free-will debates on LW recently (blame Scott Aaronson), and the usual potentially answerable meta-question "Why do we think we have free will?", I am intrigued by a sub-question, "what would it feel like to have/not have free will?". The positive version of this question is not very interesting, almost everyone feels they have free will most all the time. The negative version is more interesting and I expect the answers to be more diverse. Here are a few off the top of my head, not necessarily mutually exclusive:
Epistemic:
Psychological:
Physical:
For me personally some of these are close to the feeling of "no free will" than others, but I am not sure if any single one crosses the boundary.
I am sure that there are different takes on the answers and on how to categorize them. I think it would be useful to collect some perspectives and maybe have a poll or several after.