Courier if set to put up to 64 of something - it will place 64 regardless if it has 64 or not in it's bag.

Hi, can we get some more information? What version of Minecraft and the mod are you on, what item, modded or otherwise, were you trying to transfer, and can you replicate this bug, and if so, can you give steps to do so.

Enigmatica 2 pack on Curse forge so 1.12.2 with 2.7.0.772
As long as the Courier has at least 1 item in his bag he will fill up to 64 on destination even though he only has 2.
I'm doing this with Wood from farm and take to Furnace - Pick Coal from same Furnace, Feed the same Furnace and then a bunch of other furnaces.
On every trip he fills a furnace to 64 coal while it's only 20 seconds of a trip.

I've had this on 1.12.2 in the spring of 2019 as well but I was hoping it got fixed by now - so It's not new. At the time I was hosting a server on my own PC and i thought that may be something wrong that I've done.

Fill Up To and Put Any will have same result - full 64 stack at destination

When the math is done on first furnace :
5 in Low - 2 in Result - the furnace should end up with 7 but ends up with 12 - do doubles what has in Low and then adds what he took from result

when "taking'' from Down - it will take the sum of Result+Low In bag

So far I found a workaround by emptying the Low First then empty the Result fill the Low up to 32 while the Take is up to 64. This has stopped the coal duping :)

Found the issue, it's basically furnace for some reason making the fuel slot available when pulling from bottom of furnace, but only available for view. So I had to add a bit of code to double check that courier can actually pull from that slot and that fixed it. will be fixed with next release

When will the next version be released? Is there a temporary fix for this issue for now? KDSProm, could you please elaborate as to how you fixed this? My courier's small pack keeps filling up with stacks of 64 charcoal. Cheers.

Fixed in latest release