i havent dabbled in behavior trees at all, but i once had a character that wouldnt move at ALL, even with using the SimpleMoveToLocation function which should always work. i had the path nav mesh bounds setup it showed fine but for some reason it would not move what so ever.
i got ■■■■■■ as all hell and made a new character and got the SimpleMove function to work just fine and then it broke again when i made the characters capsule component larger than 200 in either radius or height.
so just to rule out this weird bug i found, make sure your character even move with manually calling this SimpleMove function and then make sure ur capsule component is the normal 88 height 44 radius.
sorry if this doesnt help or if im completely of topic here