At first I can put in some tiles and theres no problem then when I save my project then close GDevelop then when I open GDevelop and my project again then my tilemap suddenly looked like this:
It suddenly became small + I can’t open that tilemap again to make changes and the tilemap on the object list suddenly looked like this:
I don’t know why that happens, I was able to place a few tiles at first. The problem only seems to happen when I close GDevelop then later open it again 
EDIT: Apparently this also happens when I open/close my project(without even closing GDevelop) 
Do the examples provided with GDevelop using this object work ? (“Basic Level Editor with Tile Map Object.gdg” for example)
Can we get your project ?
That problem doesn’t happen in the example projects, only in my project . Here’s my project, it also has the tileset, the scene where the problem happens is “MapEditor_Main”
project.zip (7.4 KB)
The type of the object was not defined in the project file : strange behavior from GDevelop.
But I removed and re-added the object on the scene and everything worked perfectly until I reload the project (and the object disappeared again.
I’m investigating the issue right now. 
EDIT : It’s not really an issue but this problem happens because the HTML5 Platform (for Web games) is activated for your project (the TileMap object is not supported in this platform). So, deactivate this platform (go into the “Extensions” dialog and right click on “HTML5 (Web and Android games)” > Do not use this platform anymore). Then, you can add your tilemap object and save properly.
EDIT2 : What I said earlier should fix the problem. However, I added a fix to GDevelop for the next version so that objects not supported by one of the two platforms will work even if the two platforms are activated for a project.
I need both platforms.
So when will the update/fix come out?
Why do you need both for this project ? (I was talking about this project’s platform, not the platforms in general for all project)
The tilemap object is anyway not compatible with the HTML5 platform, so you won’t be able to publish your game as HTML5.
So if I go with the Native platform only, then I won’t be able to have my game in Android and in game sites ? 
No, you won’t. But anyway, the TileMap object is only available for native games.
Okay
So in the next version then I can use both platforms without problems?
Yes (but the Tilemap will still not be available for HTML5 games )
Ok but last question, is it possible to resize a tilemap?, because I’m making a Map Editor and I want it to be that people can change the size of the map.
Currently no (don’t know why I did not added this function, will do it for the next version too ).
Ok thx 