Strange vertices problem

Hi. So I was modeling when a strange thing occured:


See this line in the middle? No idea why is it here. That’s how it looks when I get into edit mode:


It looks like it ‘ignores’ the edge.

It’s not hanging ‘in the air’, if I delete it


I can no longer make an edge loop.

I would be grateful for the answer how to get rid of this line and what is it. Thanks.

You have created an edge over an n-gon face (with F). If you want to spit the n-gon with an edge, use vertex connect (J) instead.

Object mode shows just that edge because it optimizes edges out on flat areas. To show everything, go to object proprties -> display: draw all edges.

Problem solved. Thank you for your fast reply.