The Slime reached about 3-5% before everyone in the map got warped out without a present. The ~uptime command shows that the time of warping was approximately 19hrs since the last server check. The people who entered the room again and attacked after the warp received a present, but many were left without one. Channel 9 Edit: Another bug I've noticed is that if you already have the "Looking for Love" cash effect in your inventory, you basically receive nothing when you turn in a present to Sandman. They don't stack like other items.
The event map clears itself 3 hours after the Lovestruck King Slime has spawned. This is so that there are no occurrences of multiple slimes, and to stop people from AFK'ing in the map. I will consider adding a 3 hour clock to the map when it spawns. As for the Looking for Love item, they do stack but just do not show the number of items that are in the stack. If you try dropping the item, it will drop one, and you will still have the rest of the stack in your inventory.