I have a TileSet in which some of the tiles also have a Sprite.flip_h=true version. I created this TileSet by creating a scene with a Sprite/StaticBody2D/CollisionShape2D for each tile, and then converting the whole scene to a TileSet (I don't know if this matters).
For each tile that should have two versions, I duplicated it and changed the Sprite.flip_h of one of them. In the Scene (later converted to a TileSet) everything appears as I'd like.
In a different scene, I added a TileMap and load the TileSet. The Sprites that should be flipped (those with Sprite.fliph = true in the TileSet) don't show flipped (ie. they appear as if Sprite.fliph=false)!
Any idea of what I may be doing wrong?