This definitely seems like a Z-order issue, where your background’s sprite z-value is set either
- Too high, i.e. >1, so it is not rendered at all.
- Lower than the other objects, so they are rendered above your background.
Since it does not render at all, if I understand you correctly, even in places where there are no objects, the first one seems to be the culprit. Double check all relevant z-values; remember that if your background game object (bg) has z-value 1, and its sprite (sprite) also has z-value 1, then the sprite will not be rendered, as the sprite will then have z-value 2, and hence will not be rendered.