Can not generate APNS from Servers tab
I assume you are using MC Version 15.x
The APNS settings moved to the new UI of MC.
You can find them under the new global settings section.
-> Login to mobicontrol webconsole
-> click on the cake icon top left corner (where you can access profiles, rules, etc.)
-> click on global settings
-> you can find there the tab Apple and under apple you will find APNS