Both Mail and Calendar indicate that they are available in full screen. When I open both, then split either mail or calendar, the other program show "not available in full screen, so I can't use mail and calendar together in split view. The progress works properly in iOS 9, but not in El Capitan on a 2011 MacBook Pro.
Mel
iPhoto '11, OS X Mavericks (10.9.2)
Hi, MelYow.
Thank you for visiting Apple Support Communities.
I understand that you are unable to use certain applications in Split View. If an application is not available to be placed in Split View, this usually means the application needs to be brought out of full screen. I would suggest making sure all applications are out of full screen and try again. You may need to check other Spaces for these applications.
Use two Mac apps side by side in Split View
Cheers
mail and calendar split view
