I've followed this Knowledge Article, and nothing seems to work. https://help.salesforce.com/articleView?id=000350558&type=1&language=en_US&mode=1
Following the KA: I went to Setup -> Record Page Settings -> And have "Activity Timeline" checked. I also went My Avatar -> Record Page Settings -> And have "Activity Timeline" checked.
On an "Activity" tab on a Contact record page I see an Activity Timeline just fine. I can't figure out why it doesn't show in a Community. After the community is published the component is completely absent. I am testing as System Administrator, and have assigned/created tasks and events to myself. Not sure what else to look for. Org Wide Sharing Rules show "private". I changed it to "Controlled by Parent" but nothing helps. This is also "Health Cloud" if that makes a difference.
Fig 1: Works On a record page
Fig 2. Component dragged on to a page