How do you know it isn't an RI?? No offense, but it sound like you aren't that experienced with Bloods or even snakes in general. I could be wrong because I am only assuming.
Firstly, it is quite awkward that a Blood doesn't snatch up the mouse/rat right from your feeding tongs and you have to leave it over night. So right off the bat you know something is wrong.
Secondly, I keep my temps at the hot end for all my Bloods at 90-91 degrees and cool side at 84 degrees. Your humidity might be a little high and you might want to try about 70% and make sure the snake has a proper sized soaking container.
Other than that, you should be golden. Try to "induce" the snake to eat by bumping the side of its body with a warm mouse/rat. Or get all up in its face with the prey item. I have found this works with all my younger Bloods/Borneos. But make sure you don't over stress the snake out. There is a fine line and experience is the only way to tell. Good luck~!!