iPhone app freezes

I updated my iPhone SE 64 GB to iOS 12 over WiFi. The phone app freezes meaning it will not respond when I touch the Favorites, Recents, Contacts, Keypad, and Voicemail phone app icons. The phone app will stay stuck on whatever the last phone app icon was last used. I am still able to receive phone calls, and can use the Contacts app and the Messages app to make a phone call. Double clicking on the the home button and swiping up to close the phone app will not unfreeze it. Holding down the power button until the "slide to power off' message appears and then holding the home button until the phone resets does not unfreeze the phone app. Turning on airplane mode for several minutes and then turning off airplane mode does not unfreeze the app. Do not disturb is turned off. Turning off the phone and turning it back on is the only method that unfreezes the phone app temporarily. I connected my iPhone to my computer, backed up the phone, downloaded iOS 12 through iTunes, clicked restore iPhone, and then restored my iPhone from the back up. The phone app still freezes at least once a day. This issue never happened prior to the iOS 12 update. I use Boost Mobile as my carrier. If anyone has come across this issue and has found a solution, please let me know.