ETA: Seems like it was a bug that has been fixed now.

Hello, I feel really embarrassed to ask this, but how exactly do I smelt bars in a furnace on this server?

When I use copper or tin ore on a furnace, text pops up on the left side of the screen that says:

Bars Used: 0
Cannonballs: 0

XP: 0

I can't seem to interact with this text, and nothing else pops up that I can click or interact with to smelt a bar.

I've tried everything I could think of. I do have both (un-noted) copper and tin ore in my inventory, I have nothing equipped in my hands, I have relogged many times, I've tried using different furnaces (Lumby and Falador, can't find the one in Edgeville). I've tried using a copper ore on the furnace, then using a tin ore on it right afterwards. I've even tried on both the desktop and Android client with no luck. Am I doing something wrong, or could this be some kind of weird bug?