If I start at my profile page, and click the little friend icon next to Completed cities, I see my friends. If I click one of their avatars I see a summary of their info, and at the bottom Recent activities. But when I click any of his activity I get the message Content missing
I am able to replicate this issue.
Go to your list of friends, click on some friend, then click on some rocket.
I believe I’ve resolved this in Updates on December 11, 2023 (Release 947)