Hello nomad.edge,
Please check out the information in the following page, which outlines which apps Shared with You is available in on Mac, and may help: Keep track of shared content in Messages on Mac
Shared with You is available in the following apps: the Apple TV app, Books, Finder, News, Notes, Photos, Podcasts, Reminders, Safari, iWork apps, and some third-party apps.
To ensure Shared with You is enabled correctly on your device, please use the following process:
Turn Shared with You on or off
Use Messages settings to choose whether content shared with you appears in the Shared with You section of all available apps or only specific apps.
1. In the Messages app on your Mac, choose Messages > Settings, then click Shared with You.
2. Do one of the following:
* Turn on all apps: Click Turn On.
* Turn off all apps: Click Turn Off.
* Turn on for selected apps: Select apps. (Content sent to you with Messages will automatically appear in a Shared with You section in those apps.)
* Turn off for selected apps: Deselect apps.
You can choose whether content shared with you in a Messages conversation appears in the Shared with You section of the corresponding app. Click the Details button in the top-right corner of a conversation, then select Show in Shared with You (or deselect to remove shared content from the Shared with You section). When Shared with You is turned off, you can still pin shared content to show it in the corresponding app.
For more information, see the Messages chapter of the user guide for iPhone, iPad, or iPod touch.
Tip: You can also find Shared with You content when you search with Spotlight—it’s in the Shared Links section. See Search with Spotlight.
Thanks!