Fix race during initial Sonos group construction (#26371)

* Fix race during initial Sonos group construction

* Update homeassistant/components/sonos/media_player.py

homeassistant/components/sonos/media_player.py

@@ -337,8 +337,16 @@ class SonosEntity(MediaPlayerDevice):
     async def async_added_to_hass(self):
         """Subscribe sonos events."""
         await self.async_seen()
+
         self.hass.data[DATA_SONOS].entities.append(self)
 
+        def _rebuild_groups():
+            """Build the current group topology."""
+            for entity in self.hass.data[DATA_SONOS].entities:
+                entity.update_groups()
+
+        self.hass.async_add_executor_job(_rebuild_groups)
+
     @property
     def unique_id(self):
         """Return a unique ID."""
@@ -469,10 +477,6 @@ class SonosEntity(MediaPlayerDevice):
             self.update_volume()
             self._set_favorites()
 
-            # New player available, build the current group topology
-            for entity in self.hass.data[DATA_SONOS].entities:
-                entity.update_groups()
-
             player = self.soco
 
             def subscribe(service, action):