If you have though to have finished, well, that's not it. In fact, when designing a Behavior Tree, there must always be a phase of debugging and check if everything works as it should. Actually, on purpose I built the tree with something that doesn't work. Can you figure it out? Give it a try before keep reading.
The first problem is that, the Destination Key in the Blackboard, until the Player is not on sight, it will never get initialized. Moreover, there is another problem, when the AI enemy is seeking the Last Known Position of the player, but it is not reachable, it will fail the task. As a result, the sequence will not allow to go in the next Task to select a Random Destination. How can we fix this? Let's give it a try before we keep reading.
There are many approaches to this. For instance, you might have though to use the "Force Success...