Like the title says, I can't use voice and mobile data at the same time. If I'm on a call, the 4G icon goes away and I get a "no mobile data" message on any app that uses data. Likewise, if I'm using data and a call or text comes in, it interrupts the mobile data network.
I've tried rebooting the phone, checked all the settings I can think of, and have confirmed that there is NO simultaneous voice and data on 4G networks in four different states. Any ideas?