Most of the time this is because of the project type not being included in the view, or there is a filter that is preventing them from being displayed on the Project Requests tab.
You can edit the view and make sure that all project types are included and that there is no filter preventing them from being displayed.
1. Open the Project Requests tab.
2. Click on More Views - Edit Current View, or click on the view to change in the gray bar then Edit Current View.
3. On the first screen of the wizard, make sure that all project types are selected to be included.
4. Click Skip To on the bottom and choose filters and make sure that there are no filters that would prevent the project requests from being displayed.
5. Click Next Step. If it is a custom view, you will be able to click Finish and Save. Otherwise, you will have to give it a new name and select Save a Copy.