eyebo says:
Are you sure the map uses custom textures? Does it saw in the Track details on MX that it uses a custom mod?
It's also possible it's just signs or custom skins/car models (for GPS) that are being downloaded. Those also show up as a blue bar at top right online.
If you know for sure it's a texture mod... usually restarting a couple times from start will make the mod appear. If not, you can leave the server and rejoin and the mod should appear. Not exactly the most user-friendly way.
To clarify the issue:
1. On my desktop I made a map with custom URL mod, all textures were displayed during editing/driving
2. Uploaded the map to server
3. All textures are displayed on desktop
4. Joined the server on my laptop
5. Custom textures aren't showing, only default.
Probably because I didn't load up the map in the editor on my laptop. I did see a blue download bar and I did see it disappear. But, no special textures. After two restarts atleast.
Maybe my file is a bit large? It's 20MB in size, it's a direct link from Dropbox and uploaded on a free account.