Problem: When I load a new map all I get is blue sky.
Problem: When I'm driving on a map the road just ends with a big hole in the world.
Explanation:
This occurs because OMSI can't find some scenery items. OMSI maps are divided into square tiles roughly 300 metres square and if something is missing on the tile it won't load at all, so you get a hole there. If all the nearby tiles don't load, all you see is the sky.
Solution:
To solve this, you need to identify what is missing and make it not missing. The first step to this is to ensure that you have downloaded and installed any and all dependencies listed inside the read-me and/or download page. You may find that amendments to this list have been made on the release thread and you missed then on your first look.
If you're still finding you're missing things, the easiest way to identify exactly what is missing is to use a tool called
OMSI Map Tools. After downloading this tool, read the "Quick Guide" as this explains the basics of the program. You can then analyse the problem map and get a list of missing objects and splines in their respective tabs. From here, you can search for sources for the objects, or for people who have the same issue who may have had their issue solved by helpful people. It's best to search for identifying folder names when multiple objects are in the same folder, rather than searching for the filenames, as you stand more chance of matching release thread titles.