Seems to be a bug with this.
The following comes from my lot of BOID 209024-92.
I reserved the item for a certain user and they went ahead to purchase it. Seems that reserving it automatically changes 'for sale' to no.
I can't now seem to change that back to 'yes' - but I don't know if this is because I don't currently have any stock, or because the reserved issue is still in play. Even removing the username of the person the lot was reserved for doesn't seem to change the ability to change the setting.
Comments
In order to get it back for sale again, I had to do it in 2 steps... remove 'reserved for' name, submit changes. Then tick the 'for sale' flag and submit changes.
That's all with a 0 quantity lot.