My 2nd unit Sonicport VX (purchasing via Line6's refurb program) works fine with IOS 10.2 on an iPhone SE.
That being said, the 1st unit I received actually was pretty much the same thing @Bipai described - was okay working via USB, but the Lightning port (or 30-pin, because I also tested it with an older iPod Touch and iPad 2) was completely non-functional.
In basic testing, I noticed if you are just supplying USB power to the Sonicport without connecting to either an iPhone, nor an actual PC/Mac, the unit won't show any signs of working (you can plug in a headset, but you won't hear anything.)
Until it is recognized as an ASIO device on a PC, it will not enable even the direct-monitoring switch.
Or if you then plug it into an Apple device (Lightning or 30-pin) with a compatible App running (important, because if you aren't actually running a compatible App while trying to use the Sonicport, it will similarly appear completely dead. (and per my prior finding, if you try to connect the Lightning AND the USB simultaneously, the USB side will be disabled for playback/recording (meaning the PC/Mac will not detect the device, and won't enable it until you disconnect the Apple device.)
Make sure you at least download and run the Line6 Mobile POD (you don't have to pay for the App - leave it in Trial Mode.) After a few minutes (took me about 5) of being connected to the Sonicport, the Mobile POD App will unlock itself and all the preset tones should unlock - but it doesn't happen instantly upon the first plug-in. Before the App fully unlocked, my Sonicport initially appeared non-responsive on the Apple device, as well. Then after a minute or two, I saw the device show up in the Settings screen of the App. And a few more minutes later, all of the lock icons disappeared (you may need to be connected to the Internet for this to happen, whether cellular or WiFi.)