Server not send an event if clients number more than 3

Hello! I have a pre-match countdown function implemented. When the required number of clients enter the room (the server itself calculates the required number of clients, the properties of the room are not involved in any way), this function is triggered and the server sends messages to the clients containing a countdown. evnt.Time = 5..4..3...0 every second. Once the client gets 0, they can spawn an avatar and start playing. Everything works as it should, up to 3 clients, if I try to increase the number of clients to 4 or more, the server just not sending an events, although the function works. Those, I see that the countdown is going on, but in the bolt's log there are no messages that the event was sent, and of course the clients do not process these events in any way. Event configured as "Only Server"

private IEnumerator ServerCountdownCoroutine()
		{
			var remainingTime = GameConstants.PREMATCH_COUNTDOWN;
			var floorTime = Mathf.FloorToInt(remainingTime);

			PrematchCountdown countdown;

			while (remainingTime > 0)
			{
				yield return null;

				remainingTime -= Time.deltaTime;
				var newFloorTime = Mathf.FloorToInt(remainingTime);
				if (newFloorTime != floorTime)
				{
					floorTime = newFloorTime;

					countdown = PrematchCountdown.Create(GlobalTargets.AllClients);
					countdown.Time = floorTime;
					countdown.Send(); //not see in Bolt Console when clients more than 3
                                        Debug.LogWarning("Evnt.Time = "+floorTime);//i see this message in log
				}
			}

			countdown = PrematchCountdown.Create(GlobalTargets.AllClients);
			countdown.Time = 0;
			countdown.Send();
			matchStarted = true;
		}