Problem With the Visual Editior

So I remade my whole pokemon map into a new tile i downloaded, and after I combined two maps using the visual editor option.I tested it out if it works but the problem is the 2nd map doesn't show when im on the very top of the first map, but when I move up a little bit the 2nd map looks like its merging the first one. (I'm sorry I suck at explaining my problems i'll put pictures up)

i had this problem when i first started out. i can't remember what i did exactly but i think i just deleted the data in the connections.txt in the pbs folder for the two maps and remade it