4 vertex shape faces Good day everybody.

I've been having troubles with a phantom face that appears when moving a vertex from a figure inside. I'm not sure how to explain it.

I have this face:


And by moving a vertex inside bends the face and keeps it triangle shaped. I get the following result:


In my head it should keep the limits within the edges, but it's not doing that, I wonder if this is normal and i'm chasing a ghost or is that I missed a step somewhere.

Sorry for the nuisance ^-^
Select the face that is not behaving properly. Press 'x' and choose 'Only Faces'.
And fill it again with selecting two edges and press 'f'.

I hope this helps!