I have same problem.
In empty scene, loaded after main menu scene (even no camera, absolutely empty scene!), after UnloadUnusedAssets menu atlases, materials and collection prefabs are still loaded in memory.
UPD:
tk2d was updated to 2.0, in special empty scenes I wrote:
...
Object[] txt = GameObject.FindObjectsOfTypeIncludingAssets(typeof(GameObject));
for (int i = 0; i < txt.Length; i++)
if (txt[i].name.Length >= 18)
if (txt[i].name.Substring(0, 18) == "Interface_mainMenu"){ //my sprite collection prefab name that need to be unloaded
tk2dSpriteCollectionData t = (txt[i] as GameObject).GetComponent< tk2dSpriteCollectionData>();
if (t)t.UnloadTextures();
};
...
and rewrote tk2dSprite.cs and tk2dSlicedSprite.cs UpdateMaterial() function with this:
...
protected override void UpdateMaterial()
{
renderer.sharedMaterial = collectionInst.spriteDefinitions[spriteId].material;
}
...
UnloadTextures() function frees up a lot of memory, and rewriting of UpdateMaterial() function fixes a bug with black textures in sprite materials when scene with unloaded spritecollection has been reloaded.
P.S.: sorry for my bad English