Marques and his family are known to be settled in Leeds, but fans fear that the centre-half could walk away for nothing at the end of this season when his current 12-month deal expires.
An ever-present and reassuring presence at the back prior to jetting off for African Nations Duty with Angola in January, Marques arrived back at Leeds last month with old boss Dennis Wise having left the club and McAllister in as his replacement.
McAllister said: "Talks are ongoing, that's all I can say. There's agents and stuff involved and I don't think agents are the best friends of this club at the moment.
"But we're still very hopeful. In my court, I've only signed a three-and-a-bit-month contract here, but I've been saying to the club that I think it's in their interests to get it sorted.
"Things are going along, but it's slow. But it's going in the right direction."
Meanwhile, Palace boss Neil Warnock says that gossip regarding Marques moving to Selhurst Park is agent talk and is not paying too much notice.
Warnock says in the YEP: "It's agent talk. Agents are ringing people all the time and lots of names are being mentioned to me. So I'm not commenting on anyone. It's all annoying me now, to be honest."