how does the original temperature of liquid effect yeast and the final rise of the dough.

I made croissants with milk directly from the fridge which was around 45 degrees which i dissolved the yeast in. the final croissants did not proof well. they bloated up but looked limp and did not bake up well.

in comparison I made croissants with milk heated to 74 degrees and the resulting proofing yielded a much taller rise.

now I do rest the dough in the fridge a significant amount so I'm assuming the final temp of both doughs would be equal on the final roll out.

other then the increase in temp of the milk the procedures are identical.

just curious why there is such a difference.
the problem is cold milk gives me width while warm milk gives me height. I can't get both....

also, I've made croissants before with cold milk which yielded a tall rise its only recently that they have been going limp on me.