Would be 5 stars if it could still play a wav file when phone locks or app is minimized

I use the program to zip up .wav files and email to myself. I play the files through my phone through Bluetooth in my car to check mixes. If my phone locks the program stops or if I minimize the program to check texts or whatever it stops playing. I upgraded from the free version hoping that this would go away but it still does the same in pro. Please add this if possible.

My son is disappointed about iZip Pro -Zip Unzip Unrar Tool