If a background process is stopped, applying either fg or bg to it should cause it to continue. To do so, the shell needs to send a SIGCONT signal to the process group (not just the process) to cause it to be ready to run again.
If a background process is stopped, applying either fg or bg to it should cause it to continue. To do so, the shell needs to send a SIGCONT signal to the process group (not just the process) to cause it to be ready to run again.