Order Comment disappears?

Hello.

I am using the following command to send a market order:

ExecuteMarketOrder(TradeType.Buy, Symbol, volume, label, stopLossPips, takeProfitPips, Slippage, TradeComment)

This works flawlessly in backtest, but when running the robot live, sometimes the comment is not stored with the order.

I use the comment to keep track of orders and where they belong, and after I execute the market order, I try to retrieve the position comment on position open, sometimes it comes back filled in, other times it doesn't. I haven't been able to find a pattern, but it just happens, and more frequently with some instruments.

Is there anything I am doing incorrectly here, or should the comment not be used or trusted?

Thank you.