What causes disabled sprites and layers to be re-enabled?

[b.helyer]

Setting up menus and things, it's often useful to disable a layer. When returning to it, simply issuing a setTile call to the Tilemap associated with the layer that is disabled seems to reenable it, which is good, but it doesn't seem to be explicitly documented, so wondering what causes Layers and Sprites that have been disabled to be enabled.