Firmware upload issue, vehicle not connected after firmware upload,

I am facing issues regarding loading PX4 build file for Pixhawk 5x, black cube and even Pixhawk1.

I cloned the v1.12.3 px4 and build the file for above mentioned boards. When I upload custom build files from qgc, it says upload complete but then it doesn’t work and no option like vehicle selection, parameters etc tab shown.

I tried to upload the stable build file from internet, after uploaded it says few parameters are missing. One such is sys_autostart and some RC related parameters.

Can anyone guide me to rectify this issue?