I have been playing with the Allomancy mod, and Feruchemy mod, on a LAN world, and yesterday I got Larasium, and burned iron, and noticed there was no iron lines, same for steel, and brass didn’t show that the other player was using allomancy even though he was, and he didn’t have his copper cloud up, gold did not show me anything, nor did electrum, I was the non host player l, I was playing on Mac, the host on PC, he saw the lines just fine, we did not have any mod that effects rendering installed, so I don’t think it was that, and the host could still see the lines anyways.
Could be a duplicate of the one saying that LAN has network issues #44 (comment)

The issue is not what I thought