It wasn't considered because they didn't have time. They had to pass the case to the AC by 15th May, to avoud it being timed-out, as it would have been over 5 years ago and therefore outside their own limitation on reopening a case. They'd only opened the case a couple of months before.
But there's a doubt as to whether that date was even the valid one, as it totally depends on when the breach actually occurred. If CAS decides it was before 16th May 2014 then they'll have been out of time and i assume the case will be dropped.
Do you think City made their "irrefutable proof" document 200 pages exactly for this reason?
If UEFA accepted and let City argue it, they'd have been timed out.
If the rejected it, they've abandoned their due process and CAS are likely to reject a decision which ignored evidence.