After on of the most recent update, I could no longer print using my iPod touch five and my HP envy 5660. It had previously worked just fine, but would now not print. I reported my problem through the feedback section of the app and received a quick reply from Olga at the company. She sent me instructions on how to add my printer to the app manually using its IP address. This corrected my issues with the app and I can now print with no problems. Below is the instructions that she sent me. Hopefully, it will help others having the same issue. If it does not help with your issues, I recommend you contact the company as they will quickly email you back and try to help you.
Here are the instructions that she sent me:
1.Open the Printer Pro application
2.Tap the blue Add Printer button
3.Tap Add Manually
4.Tap IP Printing
5.Type in your printers IP address (e.g. 192.168.1.10). Note: you can find the static IP address on the printer device itself or in the Network section of its settings. You can check your printers user guide for more information.
6.Tap Next Step
After this please make sure that both your printer and iOS device are connected to the same WiFi network.
Kate Lynn 27 about Printer Pro by Readdle