I had to check the new Project page to be sure the OP didn't miss something. They didn't.
Are you serious? The Listen bus is the thing that makes metering and monitor correction play together in unison. It finally made it possible to just use Sonarworks at all times and go straight to export in the Song page.
Can it be that nobody thought it would be useful on the Project page?
As it stands, if you set up a mastering session in the Project page (which is still not complete with no automation!!), then add your room correction post-fader, all the built-in metering shows the results of the correction software, not the actual master, rendering the entire Project page's feature set useless except for DDP export.
Like my "Control Room" FR from two years ago (!!), the Listen Bus should be a universal concept in Studio One, accessible in all modes of operation, configurable for monitor control in-the-box. (Even the integration with FaderPort still controls the "Main" fader instead of the Listen Bus fader when you select "Output control.")
This seriously needs to be addressed in an upcoming update, along with some more attention being paid to the Project page as more than an amateur's "mastering" view, or else people may give up on the Project page entirely.