Debian Strech LXQT touchscreen problem

I have a c app using a touchscreen interface. When I start it using qterminal in LXQT works fine. However, when rebooting and having the c app autostarted by LXQT the touchscreen no longer works. Finger movements seem to generate mouse motion events in SDL and finger taps do not come thru. If a usb mouse plugged in it works correctly. Found out today that if I logout of LXQT and then relog back in, the c app is correctly autostarted by LXQT and everything works fine. Finger motion on screen produces finger motion SDL events and now finger taps come thru fine. Does anyone have an idea what is going wrong during the power up boot? Any suggestion what to try to get the c app to autostart in LXQT?

maybe run xev to directly see X11 event stream? Perhaps there’s something on the way through the SDL library?