I've been attempting all night to figure this one out, I've followed all instructions (including from the "FAQ & Custom map troubleshooting".
The issue is that the original Lif:YO map is mixed up with my own custom map.
I've attempted to re-upload the map 4 times. 3/4 times it gives the same mixed up the map, and the other one gives me a completely random map (second attempt to fix).

What I've tried...:
As the 'Custom map troubleshooter' suggests, I've replaced the terrain maps in my Lif:YO server directory and replaced the files there.
I've reinstalled Life is Feudal: Your own, and once again replaced the files as the instructions suggest.
I also attempted to change the terrain files in the "file manager>data>terrains". From the control panel of PingPerfect. (Just to be safe/sure..)
The last attempt I deleted everything I could find related to the map, including DB and started all the way over from deploying to connecting the DB to live-map.

So at this point, I'm lost and out of options. Perhaps there is a simple thing that I completely missed or just something that I'm unable to fix myself.
I've done this whole progress before, earlier this year and did it successfully, had no issues at all and my custom map worked perfectly.

Do you have any idea what the issue might be?

Can't tell you much more than what's on the FAQ page.
The server merges the original and custom map if the terrain files aren't replaced when the server boots up for the first time after map installation.