Hello,
As you can see in this gif, the rendering of tiles is affected by cursor position and what tiles are next to them.

They’re all on the same z position. It’s the first time I use tilemaps and tile palette but everything looked pretty straight forward to make it work. Am I doing something wrong ?
Here’s my palette :
Tilemap :
And grid :

One reason this can happen is that all the sprites are not all within the same texture. Chunk mode requires a single texture. If not already, add the sprites to the same Sprite Atlas. It may still flicker but will be fine in Play mode b/c Atlas is used then. If that’s unbearable then create a spritesheet manually.
Sorry for the late reply.
They’re not really flickering, just changing they render order depending on what tiles are next to them. No changes in Play mode. I tried atlas too but nothing changed and switch from chunk mode to individual changed something but still broken.
Here on the left is the tilemap and on the right is the palette, all tiles are placed like on the palette yet it’s random.
Same Sprite Atlas, same layer, same Z pos. But when I switch back to chunk mode it works fine.
Here’s a really weird thing when a place another time the whole palette on the tilemap.

Any clue on something I could have misconfigured ?
I don’t think putting it on a spritesheet would change anything once it’s converted back to tiles.
Ps : I love how there’s a demo scene included where there’s an empty tilemap and all sprites manually layed out included in this asset. https://assetstore.unity.com/packages/2d/environments/isometric-medieval-pack-209879
I some one can try to create a tilemap with this asset and tell me back if they succeed I would be really grateful !
Hmm. Perhaps you should check out this demo project here: GitHub - Unity-Technologies/2d-techdemos: Tech Demos for Unity 2D Features
There’s a scene in there where it’s they’ve correctly set up a z-as-y isometric scene. Examine your scene and settings versus this demo. If worst comes to worst, you could always start from that project, delete everything you don’t want, add in your own art, and you can be certain that you have the correct settings.
Would it be possible to share what your Sprite assets look like, as well as the Texture/s where the Sprites came from? If each Sprite belongs to its own Texture asset and are not in a Spritesheet or atlased, then the sorting for Chunk Mode in the TilemapRenderer would not work properly.