I’ve worked on the “short i” more than any other sound - my legal first name starts with the sound “ill”, and I have never been able to say it fluently. I wish I knew some kind of trick to make it easier, but it’s been 2 decades without any progress. I did stutter almost solely on vowel sounds as a child, and then in my late teens it switched to constants only, but the “short i” thing has been consistent.