In the Symbol Settings, you can configure the copier status for a specific symbol, which will define if the copy trading is currently active or not. You can choose to copy all trades, or copy only trades that open (Open Only) or close a position (Close Only), or to deactivate the copy (OFF). In such a case, you could receive a Deleted: Symbol is FROZEN/OpenOnly/CloseOnly Mode order status if your master tries to place an order on such a symbol on which you have defined a specific configuration.
Learn more about Symbol Settings here.