On mobile, they can sniff out explorer notes. The reason it may not work for you is because you aren’t in sniffing range of said notes. Insert this url for a map of all note locations. https://ark.wiki.gg/wiki/Explorer_Notes/Locations

Click on what map you want to see the locations of said notes on. You probably came for the island, so here it is; https://ark.wiki.gg/wiki/Explorer_Map/The_Island