We prove new non-existence results for vectorial monomial Dillon type bent functions mapping the field of order $2^{2m}$ to the field of order $2^{m/3}$. When $m$ is odd and $m>3$ we show that there are no such functions. When $m$ is even we derive a condition for the bent coefficient. The latter result allows us to find examples of bent functions with $m=6$ in a simple way.