I am running a bash script, and it is strange that after a line of calling function, echo in the called function does not print anything.

$ cat test.sh
#!/bin/bash
foo() {
    echo 1 # not print in stdout
    echo "I want to return this string"
}

main() {
    echo 0 # print in stdout
    count="$(foo)"
}

main "$@"

$ ./test.sh
0

How do I get called functions to echo to stdout?