Question about LG 32GN600

I have quite strange issue with this monitor. The higher the refresh rate I set the more visible the interlaced lines effect I get, it's especially visible at the corner of the monitor - I see black lines with a spacing of about 2 millimeters repeating through the whole panel. If I set the refresh rate to a minimum of 60 Hz - the effect seems to disappear. I tried everything from changing the driver to using different cables/ports/laptops, but nothing helped. Does anyone know what may be causing it?