Show us the System Info Report for your Lightroom on the Macbook Pro.
Lr MENU: Help > System Info...
(post a screen-clip using the [Insert Photos] above your reply window.)
OR- Are you looking at the Browser Version that is Lightroom-Web? (Does not have Masking)
Start Lightroom on the Macbook Pro by Opening from the Adobe Creative Cloud Desktop App.
Regards. My System: Lr-Classic 12.3 Photoshop 24.5, ACR 15.3.1, Lightroom 6.3.1, Lr-iOS 8.0.8, Bridge 13.0.3, Windows-11.