Absolute pointer movement not supported from libinput

I have a system set up on a Raspberry PI 3 B+ running the Boot to Qt stack.  I have an LCD connected via HDMI and USB.  The touchscreen is detected by libinput and appears to be working great, except that the touch movement is not been recognized by Qt.  Pen up/down works fine and so if I also attach a USB mouse to get the cursor in the right place, the touch will "work."  Udev is setting the variable ID_INPUT_MOUSE and the events from libinput appear to use the enum LIBINPUT_EVENT_POINTER_MOTION_ABSOLUTE.  The Qt stack does not handle this event.  I can disable libinput and evdev, and get the touchscreen working with tslib, but it seems like if this one message would be handled, it would work out of the box.  For reference, this same issue occurred also with a PCAP display connected similarly.