Updated my iPhone 8 plus to IOS13, my phone keeps changing my number format from 01234 567890 to 01 234 56 78 90, so far i have changed my location from UK to USA back to UK. I have to do this every morning. That works, however, an hour later its changed again !!!! Gone into Settings-phone- turned off Dial Assist, total re-install of IOS13 using my Mac, gone into iCloud to make sure my settings are correct country/region set to UK, reset all settings. It's not only my iPhone but my daughter's iPhone XR. She called me yesterday from 3 miles away but came up as a Belguim telephone number +32 234 56 78 90.