One more fix... if you have group names with spaces this will throw the field number off and you'll see the modification time preceding the mark name.
Adding '-n' to the ls command works around this by causing the group id to be printed instead of the group name and all works, i.e.:
\ls -ln "$MARKPATH" | tail -n +2 | sed 's/ / /g' | cut -d' ' -f9- | awk -F ' -> ' '{printf "%-10s -> %s\n", $1, $2}'