It has come to my attention that a few people cannot print from the Apps to their AirPrinters, this is due to a number of possible things.

1. Apple forces developers to use the latest SDK's, developers have zero control over this.

2. Apple have forced all developers to submit 32bit and 64bit binaries for all apps, they will reject all apps that only have 32bit binaries, what this means for you is this, if you have a 64bit device and the app was 32bit then the device ran in an emulation mode which meant everything was 32bit and things worked nice, once you submit 64bit builds the app will run in native mode meaning all drivers and code must run in 64bit, this could also mean you need to update the firmware of the printers for this to work.

https://discussions.apple.com/message/27135002#27135002

If you find that you cannot AirPrint from the apps then make sure your running the latest firmware for your printers, check to see if your device is 64bit, iPhone5S and better is 64bit, the latest iPads are 64bit too.

A workaround if you have a PC/Mac email the PDF of the item your trying to print to the PC/Mac and print it from there.