Arayas' RoExtended ProMods Road connection, available at www.roextended.ro
contains a compatibility fix that allows other maps, like Antarctica to work with
ProMods 2.40

Since You say this only happens with ProMods, I am wondering when You generated ProMods def file, did You select High/Ultra draw distance, or did You leave it on Standard? I suspect with standard draw distance, You might get that effect.