Audio Quantize from with the Arrange window is extremely hit and miss - it will either work, or it won’t do anything.
On a session today I imported a drum track - so the file was converted to a WAV at the current session rate by Cubase.
I turn Audio Quantise on try and quantise the file. Nothing happens.
So I bounce the audio in place (in effect simply creating a brand new identical copy of the original audio) and voila - it will now quantize!
It’s always been like this - some audio works, some doesn’t. Bouncing will often fix it, but not always - sometimes I just have to give up…
It’s like with the Audio Alignment tool - a half finished feature that can work but usually doesn’t, so you give up and do it manually while cursing the time you’ve wasted in the process.