UPDATE: I've discovered a workaround!
UPDATE 2: I've discovered another bug. . . See the bottom of this thread.
So, I haven't seen anyone talking about this particular mining bug, but it's been happening more often leading to me wanting to mention it. It may be related to the whole four ore won't smelt after processing gems/moonstone shards bug, but it honestly seems kind of random whenever I've actually paid attention to it, so I'm not sure.
THE BUG:
Basically, I've been doggedly grinding gold ore, rubies, and moonstone shards. Whenever I fill up a cart with these ore, I return to smelt them at the furnace. Despite me having plenty of stokes left, my furnace seems to randomly go back and forth on whether it wants to smelt four or five gold ore to make one bar. I have had numerous instances of going to smelt with plenty of gold to make two or three bars, and yet when I go to pick up my smelted items, I only have maybe one or two bars and some ore leftover, as well as some stokes remaining.
I thought it might have been relevant to the aforementioned linked bug, but after watching it a little more closely, it will sometimes still make bars using four ore even after smelting gems/shards, and sometimes it doesn't. At this point, it seems random but leans slightly more towards the linked bug. The first bar it makes will always use only four ore, so long as I have furnace stokes remaining, giving weight to the linked bug since those ore are at the front of my cart.
Gold ore takes WAY too long to mine for me to continuously lose out on gold bars like this, and I don't want to drop valuable gems nor any shards. Losing out on premium currency is simply out of the question. :'D
ADDITIONAL BUG STUFF:
I've noticed that trying to buy more stokes in the middle of smelting will usually result in errors, requiring the page to need to be refreshed, and the stokes may or may not have actually been purchased and applied. It can take several attempts and refreshes and usually takes another smelting cycle to actually apply.
I have also been keeping one spare ore in my cart to drop whenever I get stuck with four ore that can smelt but won't to combat that OTHER mining bug that still hasn't been patched. Note that this glitch still happens regardless of whether gems/shards have been smelted previous to the metal ore in question.
NEW BUG:
Okay, I know it's been a while since this was updated, but I haven't really had a reason to until now. I figured it'd be better to attach this bug here for easier reference.
I had just returned to the furnace and had one stoke left. My ores began smelting and I got a bar. I went to restoke the furnace, got the usual error message, and refreshed the page. I only had one stoke again instead of six (this isn't the new bug; this one is a known and recurring issue). However, as my ores smelted and created a new bar to use up the one stoke, causing me to restoke again at which point I successfully got six stokes, I noticed that my ores had not been depleted. I somehow got a free duplicate bar of Chaosium from the restoking bug. I had consumed four ore total and had yielded two bars due to the restoking glitch. I don't know if this has happened before. It may have and I simply wasn't paying attention.