We noticed that recently, and for some users, profile pictures are not being displayed when the People web part is rendered in the page.
If you are experiencing this issue, please follow the instructions described below.
- Copy the link to a profile picture that is not rendering
- Paste it in the browser
- Wait for the authentication window
- After loading the image refresh the page with the web part
If the issue persists after executing the steps above, please follow the steps described in these two articles from the Microsoft Tech Community.
Bad cookies and the Office 365 Admin Center
"400 Request Too Long" when navigating to profile
BindTuning is working on new ways to get the user profile picture and will soon provide a new version of the web part with multiple profile picture providers to avoid this issue.