Are you talking about your Outlaw (Combat) setup? It is a lower priority than your Assassination setup, so some things are being locked in for Assassination. Any lower priority setup will do the best it can while working around the results of your higher setups.
If you re-order your setups to put Outlaw on top (drag and drop using the list on the left to change order), you’ll see that it recommends no changes from your current setup.
Sometimes it can be more optimal to share a good item between your specs, even if the gems/enchants aren’t perfect for all of your specs. The assumption here is that you won’t constantly buy new gems and enchants and replace things every time you change specs.