I've found all of the gnomes everytime. Sometimes the volume of their speech is soft due to lag in the game or louder tones like in a battle. Treat it like the dog that won't find a dig spot if enemy are nearby. The Gnome won't be heard if combat ensues. Try reducing the sound settings of music vs. speech etc. For the cheat guides, if only they inserted pics of locations and not descriptions as a pic is worth more than 1,000 gnomes
. Not vids, as they take too long and are not to the point. Did I also mention ads that interrupt vids. Everyone does not have money to go ad free!
Could it also be the co-op gamers own game glitching the other persons?