I've got the same setup - I'm using the USBC connector it came with which works perfectly - are there any advantages with using the display port cable?Just received my new Mac Mini M1 16gb 1T (late 2020) Refurb. Saved about $250.00. Connected to a new LG 27UN850-w with the display port cable supplied with the monitor. Everything is working great.
Thanks to everyones suggestions for this setup.
KenK