Audio distortion in video replacement

We just finish a mix off a new song that I need to insert in a video using cubase “Replace Audio in Video Files”
but when we try we have distortion in the audi … sound like a over saturation but the mix sound perfect with a regular mixdown … is there a lvl somewhere ?

Don’t wanna put pressure but it’s now 4:33 PM and the clients gonna be here at 6:00PM … plzzzzzz help !!! LOL