Why am I unable to add anchor to arView scene after using removeAll()? - swift

Question

I'm trying to add and remove an anchor to my scene, but after removing it I'm unable to add it again. This might be because of the anchors added to the scene in the session function, but I'm not sure.
Do I need to run the session function again to add the anchorEntity to the scene again(not managed to do it due to some errors), or is there something else I'm missing...
Here is my code:
import UIKit
import RealityKit
import ARKit
class fvBoat: UIViewController, ARSessionDelegate {
#IBOutlet var arView: ARView!
let fvBoatAnchor = try! Vessel.loadFvBoatScene()
var imageAnchorToEntity: [ARImageAnchor: AnchorEntity] = [:]
override func viewDidLoad() {
super.viewDidLoad()
let fvBoat = fvBoatAnchor.fvBoatObject as? Entity & HasCollision
arView.installGestures(for: fvBoat!)
fvBoatAnchor.generateCollisionShapes(recursive: true)
// arView.scene.addAnchor(fvBoatAnchor)
arView.session.delegate = self
}
func session(_ session: ARSession, didAdd anchors: [ARAnchor]) {
anchors.compactMap { $0 as? ARImageAnchor }.forEach {
let anchorEntity = AnchorEntity()
let modelEntity = fvBoatAnchor.fvBoatObject!
anchorEntity.addChild(modelEntity)
arView.scene.addAnchor(anchorEntity)
anchorEntity.transform.matrix = $0.transform
imageAnchorToEntity[$0] = anchorEntity
}
}
func installGestures(on object:ModelEntity){
object.generateCollisionShapes(recursive: true)
arView.installGestures(.all, for: object)
}
func leaveScene() {
arView?.session.pause()
arView?.session.delegate = nil
arView?.scene.anchors.removeAll()
arView?.removeFromSuperview()
arView?.window?.resignKey()
arView = nil
}
#IBAction func leaveScene(_ sender: Any) {
leaveScene()
}
#IBAction func addAnchor(_ sender: Any) {
arView.scene.addAnchor(fvBoatAnchor)
}
#IBAction func clearScene(_ sender: Any) {
arView.scene.anchors.removeAll()
}
}