Strange behavior of functionalDerivative()

Hey all,

I've encountered the issue where functionalDerivative() gives a wrong result:

clear
syms x(t)
f = diff(x, t)^2 * x^2
functionalDerivative(f,x)

results in

- 2*x(t)*diff(x(t), t)^2 - 2*x(t)^2*diff(x(t), t, t)

while it should be (at least if my knowledge of partial derivates is still correct)

2*x(t)*diff(x(t), t)^2

How can this be?

If encountered this while trying to get the dynamics equation of a system using the Lagrangian approach.

Interestingly this error leads to -dL/dx = 0 producing the correct end result, while usually the equation d/dt( dL/ddiff(x,t) ) - dL/dx = 0 should produce this result. (with L=T-V, T being the kinetic and V the potential Energy of the system)