Fix: Turning the bind of the ShippingMethodManagerInterface to a singleton, so that it can actually resolve the shipping methods

src/Providers/ShippingServiceProvider.php

@@ -154,7 +154,13 @@ class ShippingServiceProvider extends ServiceProvider
         // run before the Shipping::extend() calls below, which resolve —
         // and the facade then CACHES — whatever's bound at that moment).
         $this->app->booted(function () {
-            $this->app->bind(ShippingMethodManagerInterface::class, fn ($app) => $app->make(ShippingManager::class));
+            // A singleton, not bind(): the queue worker clears every
+            // facade's cached instance before each job
+            // (Facade::clearResolvedInstances()), so with bind() the Shipping
+            // facade then built a fresh, empty manager — without the drivers
+            // extended below — and every queued job (tracking, voucher sync)
+            // saw no carriers at all.
+            $this->app->singleton(ShippingMethodManagerInterface::class, fn ($app) => $app->make(ShippingManager::class));
 
             // Shipping::extend('acs', fn ($app) => $app->make(AcsRateDriver::class));
             Shipping::extend('box-now', fn ($app) => $app->make(BoxNowRateDriver::class));

src/Shipping/Carriers/Elta/EltaFulfillmentService.php

@@ -278,6 +278,13 @@ class EltaFulfillmentService implements CarrierFulfillmentInterface, IssuesVouch
 
     public function trackShipment(Shipment $shipment): Collection
     {
+        // ELTA tracks a multi-parcel send by its main voucher only — an
+        // extra parcel's own number is rejected ("Λάθος ΣΥΔΕΤΑ"). Its
+        // history is the main voucher's, which is tracked on its own row.
+        if (! $shipment->is($this->masterOf($shipment))) {
+            return collect();
+        }
+
         $response = $this->client->getTracking([
             'web_vg' => $shipment->tracking_reference,
             'pel_code' => config('elta.apost_code'),