Unable to load in today extension mostly appears when:
Debug your app extension to find out the exact problem.
Refer to Xcode's Debug Gauge for Memory and CPU utilization.
Edit:
Debugging today extension
You can debug your extension the same way you debug your main project. Just select that particular target scheme
in your Xcode and run the project.
Now try using the breakpoints and other print statements in the extension’s code and you are good to go. Happy coding..😊