Layer disappeared in the layers list

My image consists of a single layer (I believe). However, in the layers section there are none. I can still modify the current layer opacity and other properties.

How do I make the layer reappear?

Out of curiosity, I have

  • Duplicated the layer (the duplicated layer appeared in the list)
  • Ordered the layer to move to bottom (the program crashed!)

Update:

I did something and now the layer list appears as it should...