Map Glitches when attempting to update

I run a Java edition MC server through MC pro hosting and we keep a large world map in the city we are building and like to update the maps as new structures pop up. Recently during the snapshots starting back in 20w18a and beyond that when I attempt to update the map it shows up on the map as if someone ran a missile strike through the area despite there being no distortion in the actual world. Basically it ruins the map and is hard to see.