Factorio Forums

Easier to just see it. It seems to be on higher latency servers (this one showed about 130ms in the server list).
https://youtu.be/MBRTNGftSY4

If I quickly shift+left click twice where an item is, it'll pull the one I clicked on and then the top-left-most stack available after pulling the one I clicked on.
I saved the map, played locally, and didn't experience the issue.
I've experienced it on more than one server.
Clicking slowly, as shown, doesn't exhibit the issue.

Thanks for the report however this is simply how latency is handled. Because of the delay between you clicking and it actually happening in the game, the logic does not know for sure which inventory slot and item you actually are trying to move. So, if by the time the action runs the slot is different, it does a "best-guess" attempt at what it thinks you tried to do.

Ah, ok. Thanks for the explanation, too. It's always interesting. I don't know of other dev teams doing that.