Ryu Combo Glitch Vs Ibuki?

I was in training mode using Ryu, trying some combos. The bot player was ibuki.
I tried to do the following combo:

Crouching medium punch - Crouching medium punch than Crouching medium kick.

But the Crouching medium kick never links. The move does not come out, or Ibuki blocks.

I know the link is kind of hard, so I tried many times with no success. So I was curious, I changed the bot character. That’s when I started getting the combo right. I tried, Dan, Yun and Guy, and can do the combo easily.

But when I choose ibuki, nothing, it never links.
Does anyone know this? Is it just a bug, or is there different recovery for different characters (something I never heard of).

I’m using Super Street Fighter IV Arcade Edition PC (Steam), with fps fixed option.

yep that combo isn’t normally possible on a standing Ibuki beacuse her front leg moves in slightly
it is possible after a early J.hp ( try to hit her head ) beacuse you end up closer to ibuki then you can walk due to her hitstun
also possible after a dizzy beacuse you hit a different part of her body

I thought frame data was enough to know when you can hit. cr medium punch links into cr medium kick (since it has frame advantage enough for the startup of the medium kick to hit).
But then we have to take into consideration the range of the hit. Which is strange because Ibuki does not get hit, and other characters do. I did not know characters had different hitboxes in the legs. Just size.

unfortunately every combos and situation has to be tested on every character to know witch one hit. Its hard to make generalisation since every character has different hit box. I do remember testing your combo against ibuki and the c.mk was blocked for some reason. A guy like Daigo has so much experience and match up knowledge he usually know whats going to work in different situation. No substitute then going in training mode and testing what work and what dont
but with the size of the cast now its a lot of time investment.

Other thing to take into consiration when testing combo: All character will react differently after different type of knockdown ( they have 2 different behavior , depending if you grab them or knock them down with Tatsu, sweep or srk.) Character will react differently if they are crounching or standing etc