Controller not recognized as SDL_GameController

I’m running an ubuntu 1806 VM.

I have a controller that I need to add a custom mapping for.
The controller is recognized in jstest-gtk, and I can alternatively create a mapping using the SDL mapping tool on the same laptop Windows side.
I can also talk to this controller using the HID API.

However, I cannot seem to make SDL recognize it as a controller.
SDL sees the device as a joystick, but not a game controller.
I can loop through each joystick it recognizes, and call SDL_IsGameController on the joystick index, but it always returns false.

How can I make this controller be recognized as more than just a joystick ?

Solved the problem.
The tool I was using had 0’d out the last portion of the GUID, so it wasn’t recognizing it. Using the button mapping tool that ships with SDL2 provided the correct GUID, and I was able to get the gamepad to open.