I am surprised to hear people saying it's an issue for Pre-Chek, Global Entry, etc.

I also have a generational modifier at the end (I'm a II). Everything works in any of those combinations, middle/no middle, II included/not included, MR in the middle randomly, etc. I think all TSA cares about is First/Last and DOB matching your KTN with some degree of messiness allowed. Of course no one would ever comment publicly on what they will accept and what they won't.