v1.6.10

I have a recipe on Nauvis which takes 61x stone furnace, 12x coins, 39x bullets, and yields -1000% for 1x slowdown capsule, 2x burner drill, 4x heat pipes.
I was trying to fill up the inputs to get bronze/silver stars, and for whatever reason the recipe completes with just 12 coins and no other items (I get the partial production credit, and dumping 120 coins or whatever gives me the right items, it just ignores the inputs). The trade has a total value of 54 coins.

Update: I have another trade, which is 2x engine, 1x coin -> 2x grenade (+5%)
Same thing happens - I place one coin, the trade is completed and I receive the grenades. However it will ONLY trigger if the hex inventory has zero grenades.

I am able to reproduce the bug doing what you say causes it. Will have it fixed in the upcoming 1.7.0 rebalancing update.

Great! Glad you're always on top of stuff. Still one of my fave mods.

I actually have another similar bug; there's a core that takes 2x red belts as input at -495%, output is 2x water barrel, 2x offshore pumps. I put the two belts inside, they disappear, and the productivity bar makes no progress. No other recipes are enabled here.

I am unable to reproduce that one. There are likely other factors causing that to happen. Don't know if it's migrations or core logic, but I'll try to fix that before releasing 1.7.0.

Shouldn't be migrations - I tend to start over every time I update. I'll keep an eye out when I updated.
Could it be related to the water barrels themselves? I know base Factorio has special rules when assembling filled barrels with productivity from mods

I have a 2 Iron Chest + 3 Coin -> 6 Empty Barrel recipe where I managed to trigger that bug. With only coins in the hexes inventory, it spat out empty barrels.
Trade is at +85% productivity.

edit: I swear I just got some fish from another trade that didn't have any input items in the hex.

I fixed the free trade proc bug for 1.7.0, which should be releasing either tomorrow or in two days after I get the quick rebalancing changes done.

Danjen, I tried following your steps with your exact items in a trade (used /add-trade) and was unable to reproduce the issue.

s0vr9000 - I was able to track down my "bug"
After a bit of testing, I discovered I had a loader point outward, with "use filters" set to blacklist none
So in other words, it was outputting the belts onto the ground as I was placing them into the inventory and I didn't notice them piling up, and also why it worked eventually