OK - let’s step back for a second and ignore the Docker. Make a change to detectnet.cpp or detectNet.cpp outside of Docker. Then if you build the project outside of Docker, do your changes take effect when you run detectnet program outside of Docker?
# run this outside of container
cd jetson-inference/build
make
sudo make install
cd aarch64/bin
./detectnet images/input.jpg images/test/output.jpg
Then if that works as expected, run docker/build.sh again. If you run sudo docker images, do you see the updated jetson-inference container with a recent ‘created’ date? Can you then try docker/run.sh and post the log of it starting?