This approach should work.
Add a variable called tag of type integer to your blueprint.
Initialise this with a unique value say 0.
Then use the get all actor by class node
Loop over each item with a foreachloop
Take the element pin an connect it to a get tag node. Make sure context sensitive is unchecked
Then use a conditional statement to compare your tag value to 0.
If it matches then you have the reference to the instance of this class.