No element nvvidconv when launching gstreamer from systemd service

I have gstreamer application for video streaming. However I am not able to run it as a systemd service. It always complains about missing nvvidconv, however when I launch the same application from terminal everything works fine. Seems like something wrong with plugins path/plugin cache but I am not sure what exactly.

We have tried rc.local and it works fine. Please take a look at:
omxh264enc and nvvidconv NOT working unless... - #22 by DaneLLL