I am totally new at testing apps on devices, especially the Sony Xperia. I am testing apps using the Android emulator, but I have now a Sony Xperia. First I have connected
For me, it works when combining Damir's & Michell Bak's answers.
First need to change device form MTP mode to MSC mode as Damir mentioned, then download and install driver to your PC as Michell Bak mentioned.
Most new Sony device default setting USB connection mode to MTP and the setting location is different from other android devices. Besides, driver can not install automatically and need to download form official site.