iPhone app not recording "visits" using CLLocationManager delegate - swift

Question

I'm relatively new to Swift and self-taught, and I'm currently having issues with recording Visits using a swift app.
Relevant parts of AppDelegate:
import CoreLocation
class AppDelegate: NSObject, UIApplicationDelegate {
let locationManager = LocationManager.shared
func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey : Any]? = nil) -> Bool {
locationManager.startMonitoringLocationVisits()
print("AppDelegate just ran")
return true
}
}
Relevant parts of LocationManager:
import CoreLocation
class LocationManager : NSObject, ObservableObject, CLLocationManagerDelegate {
static let shared = LocationManager()
//New location manager
var locationManager = CLLocationManager()
//Seconds between location acquisitions in background
var locationInterval = 120
override init() {
super.init()
locationManager.delegate = self
self.locationManager.desiredAccuracy = kCLLocationAccuracyBest
self.locationManager.activityType = .fitness
self.locationManager.allowsBackgroundLocationUpdates = true
}
}
func locationManager(_ manager: CLLocationManager, didVisit visit: CLVisit) {
print("received a visit")
//Code that sends a notification every time a visit is recorded
print("attempting to save visit")
self.saveVisit(visit: visit) //Code that saves details from the visit to CoreLocation
}
public func startMonitoringLocationVisits() {
locationManager.startMonitoringVisits()
}
The app compiles and runs fine on my device (iPhone 13 pro running iOS 16) but never records any visits. I've tried an example app I found online and that works correctly on my device, so it must be an issue with my code, but I can't figure out what. I also have a background refresh task recording location coordinates every few minutes in the same app that works correctly, and I'm hesitant to start radically changing location manager code to debug the Visits feature since I'm worried I would break the background task feature. Any advice or direction is appreciated!