Locate your device in a Finder/Locations window, similar to a volume/drive, select and let it load info, then drag/drop that .ipa from another window directly into the first one. You might see a green + icon, then release. Find it on your phone, waiting for it to finish.
Thanks, I also found that from xcode (11.1) I could select Window/Devices and Simulators, then select my 'Device' and drop the .ipa file in the area showing old version. As you do it, xcode higlights a 'rectangle' around all the app names it found.
This seems to work fine for Developer provisioning but NOT for Adhoc provisioning. You get the green PLUS but then nothing happens.
For Adhoc builds,
- open your device information panel in XCode | Devices and Simulators | Devices | Connected
- drag onto the Installed Apps section