FreePBX - Queue Toggle *45 doesn't work

I am having trouble with a queue that I have created whereby I want to use Dynamic Agents to login to the Queue.

I have read everywhere (and can also see in feature codes) that *45 should act as a toggle to log you into and out of all the queues that you should be assigned to. Problem is *45 doesn’t work as a feature code, I can use pretty much all the other feature codes on the system without issue.

I can also log into and out of the queue using the queue number and ** or * then entering the extension number and #.

However the goal is to have one button (preferably linked to a BLF key) which can toggle the phone in and out of said queue.

I haven’t got the system setup as users & devices and wondered whether that was a required step in getting this working?

Can anyone shed any light? Happy to answer any questions on the setup if I haven’t given enough info.