Level Generation collision checking erratic

I'm trying to adapt a level generation tutorial and I've stumbled on checking collisions between rooms. I've spent a few days searching but can't find answers that particularly help, so I think there might be a few overlapping issues. Right now, most of the time it works fine, but every so often it places a room directly inside another room, and I'm baffled. I know it's not a great idea to just copy tutorials without fully understanding it, but I'm not sure what to even start learning about.

The idea is to place a start room, pick a doorway of the room, create a new room and position/rotate it so doorways match, then continue adding rooms until the limit is reached. If a room has no legal position, it'll restart.

This is taking place in a coroutine - something I don't fully understand, but I believe we're using it because physics requires a frame (right?). In GenerateLevel(), the PlaceRoom() that's called attempts to instantiate a room prefab, selects room nodes, runs PositionRoomAtExit(), then runs CheckRoomOverlap(room). If it fails, it destroys the game object, sets resetLevelGen to true, which should call ResetLevelGen() in the coroutine.

I'm not certain why it works most of the time, but once in a while just fails like this. Any help would be greatly appreciated!

 private void Start()
  {
      levelGenCoroutine = StartCoroutine(GenerateLevel());
  }
  
  IEnumerator GenerateLevel()
  {
      //Declare some time intervals to wait for things to update before actually checking physics.
      WaitForSeconds startup = new WaitForSeconds(1);
      WaitForFixedUpdate interval = new WaitForFixedUpdate();
      //Wait a sec to let Physics exist.
      yield return startup;
      //Place Start Room
      PlaceStartRoom();
      yield return interval;
      //Figure out how many rooms we're placing.
      int roomsToPlace = Random.Range((int)numRoomsToPlace.x, (int)numRoomsToPlace.y);
  
      //Place rooms one by one.
      for (int i = 0; i < roomsToPlace; i++)
      {
          PlaceRoom();
          yield return interval;
          if (resetLevelGen) {
              ResetLevelGen();
              break;
          } 
      }
      /////In theory we can place the end room here.
      Debug.Log("Level Generator Finished");
      WaitForSeconds wait = new WaitForSeconds(5);
      yield return wait;
      ResetLevelGen();
  }
  
  void PositionRoomAtExit(ref Room room, Exit newExit, Exit targetExit)
  {
      //Position this room at the origin.
      room.transform.position = Vector3.zero;
      room.transform.rotation = Quaternion.identity;
      //Rotate the room to meet the rotation of the target.
      Vector3 targetEuler = targetExit.transform.eulerAngles;
      Vector3 newEuler = newExit.transform.eulerAngles;
      float deltaAngle = Mathf.DeltaAngle(newEuler.y, targetEuler.y);
      Quaternion oldRotation = Quaternion.AngleAxis(deltaAngle, Vector3.up);
      room.transform.rotation = oldRotation * Quaternion.Euler(0, 180f, 0);
      //Position room to meet the doorway
      Vector3 positionOffset = newExit.transform.position - room.transform.position;
      //I'm not sure if this'll fix anything, but I'm rounding the position to be sure.
      room.transform.position = targetExit.transform.position - positionOffset;
      Vector3 snap = new Vector3( 
          Mathf.Round(room.transform.position.x),
          Mathf.Round(room.transform.position.y),
          Mathf.Round(room.transform.position.z));
      room.transform.position = snap;
  }
  
  bool CheckRoomOverlap(Room newRoom)
  {
      Bounds newBounds = newRoom.RoomBounds;
      newBounds.center = newRoom.transform.position;
      newBounds.Expand(-0.1f);
  
      Collider[] colliders = Physics.OverlapBox(newBounds.center, newBounds.extents, newRoom.transform.rotation);
  
      if (colliders.Length > 0)
      {
          //Ignore collisions with current room
          foreach(Collider c in colliders)
          {
              if (c.transform.parent.gameObject.Equals(newRoom.gameObject))
              //if (c.transform.gameObject.Equals(newRoom.gameObject))
              {
                  continue;
              } else
              {
                  //Debug.LogError("Collision Found at: " + newBounds.center + " and " + c.transform.position);
                  Debug.Log(newRoom.name + " at " + newBounds.center + "(andshouldbe) " + newRoom.transform.position + " colliding with " + c.transform.parent.gameObject.name);
                  return true;
              }
          }
      }
      return false;
  }
  
  void ResetLevelGen()
  {
      Debug.Log("RESTARTING LEVEL GENERATOR");
      foreach (Room room in placedRooms)
      {
          Destroy(room.gameObject);
      }
      placedRooms.Clear();
      resetLevelGen = false;
      StopCoroutine(levelGenCoroutine);
      levelGenCoroutine = StartCoroutine(GenerateLevel());
  }