MonoGame sprites not consistently drawing

Please don't mark this as a duplicate of my previous question which was asked anonymously. this is a reattempt because i cannot edit the first attempt.

What I have so far is: - randomly generated tile set with items on SOME tiles - one creature spawner that spawns up to 5 creatures which can be controlled by the player - the ability for creatures to pick up items and bring them back to the spawn and store them for later use

What I am noticing is when i launch the game, it doesnt always show all the sprites. Sometimes the spawner is missing, or the creatures, or the GUI. ANd when things DO appear, if i tell the creatures to pick up anything, other items on the ground randomly appear and disappear. even the spawn sometimes disappears! what I do notice is that when i have multiple creatures, some will disappear when crossing invisible lines but not all of them. i forced two creatures to go east at the same speed and time, and one vanished and the other didnt.

If you have any ideas as to what might be causing this, please let me know. if you have any questions, i'll try to edit to appease you.

thanks for reading!

I have my draw method like this:

GraphicsDevice.Clear(Color.CornflowerBlue);

// TODO: Add your drawing code here

spriteBatch.Begin(SpriteSortMode.BackToFront,
          null, null, null, null, null,

          camera.GetTransformation());          

worldEntity.Draw(spriteBatch);

guiManager.DrawGUI(spriteBatch);

spriteBatch.End();

base.Draw(gameTime);

for the world entity... its draw method systematically goes through each tile in the world and calls its draw method. the tile draws itself using

Vector2 topLeftOfSprite = new Vector2(this.X, this.Y);
Color tintColor = Color.White;
spriteBatch.Draw(tileTexture, topLeftOfSprite, tintColor);

and then proceeds to call the draw method of any items on it.

creatures and items have very similar draw methods.

the gui also draws itself in a similar fashion.

what i DO notice is that ive NEVER seen ground tiles vanish, only the items on them or creatures in the world. Could it be their Z isn't set appropriately?