Check if the below link help, IF you are looking for Image Classification Wizard:
I had a similar issue with the Classification Wizard being grayed out in ArcPro. After a lot of trial and error we discovered it was due to the fact that I was not creating my projects using the Map.aptx template. Once I started using the Map.aptx template, the issue disappeared.
Nicky, even the buried suggestion for the only person that seemed to get it to work was to start their project with the 'map.aptx' rather the 'blank' one. check that comment and see if his suggestion works for you