Yeah it’s a highly compromised product.
I have tried LG 32ud59-B & LG 32UD60, both of them has the same issue .. I used EDID Manager to read their firmware and the result shucked me :
measurement scale 600mm x340mm = 27'' .
so the problem is not windows or MacOS but the firmware or maybe the real scale measurement and I will gonna test it also this week to see what's going on since I don't have real Ruler