I have also been having problems with mith bars using the coal bag and stamina potions. I'm not sure if I have it setup correctly, but this is how I set it up:
-Inventory: coal bag(empty)
-furnace: empty
The bot starts correctly by withdrawing 2 inventories of coal (27 in coal bag and 27 in inventory) and depositing them. It continues fine by banking and taking 27 coal (in coal bag) and 27 mith ore in the regular inventory. However, the next time it banks instead of taking an identical inventory of 27 coal in coal bag + 27 mith in inventory it takes another double coal inventory. This works for a while but eventually the coal stacks up and it reaches the limit in the furnace. When this happens the bot just keeps trying to deposit the coal.
There is also another problem which occurs when the bot is withdrawing coal from the bank to put in the coal bag. After taking the coal out, the bot stays idle for almost 2 seconds with the mouse hovering over the inventory button. I'm not sure if this is part of some playersense anti-ban, but it is pretty suspicious and inefficient.