Open the BP_Elevator and create 2 new variables the first one a float called Up Amount and set it to 700. Then create a vector variable called Start Location and set it to replicated.
Copy the image below.
Next open the Elevator timeline in the event graph shown below
Select the last point on the graph and set its value to 1 like shown below
Then copy the image shown below
This will fix the elevator and you can now control how high it will go with the Up Amount variable.