Question Why does systemd-cgtop batch mode only output the result of the 1st iteration?

[Bitpalast]

Why does

/usr/bin/systemd-cgtop -c -n2 -b > test.txt

not send the second iteration or at least the first and second iteration to the file, but only the first and then quits. It seems that "batch mode" does not make any difference to the command. Only in interactive mode I get to the nth (2nd) iteration.