Cloud ML Service account cannot access Cloud Storage and is not listed in IAM & admin panel

If someone finds this issue, @freeCris wrote the solution in the question. I decided to write this down as I read all the documentation in the answers to find nothing useful and then realized he wrote how to solve it in the question itself.

For those wanting to fix this, just run (make sure you don't have resources in ML Engine such as models and versions):

gcloud services disable ml.googleapis.com

And then run:

gcloud services enable ml.googleapis.com

You'll get a new service account that this time is listed in your IAM console. Just add it to your GCS bucket and it'll work now.