Lost mind while Meditating I'm practising Vipassana meditation and I noticed that most of the time my mind thankfully doesn't wonder about things (past, future, judging).

But I notice that my attention is not really sharp. It's like my mind its in standby not really paying attention to anything in particular. I lost my attention of my breath, sensations, etc.. but not because of wondering.

What's is happening?. Could I get further information about this issue?
That sounds like the hindrance of "sloth-torpor". There are lots of ways to counter this.

The Five Mental Hindrances and Their Conquest: Sloth


  Six things are conducive to the abandonment of sloth and torpor:
  
  
  Knowing that overeating is a cause of it;
  Changing the bodily posture;
  Thinking of the perception of light;
  Staying in the open air;
  Noble friendship;
  Suitable conversation.
  


Mindfulness, investigation of reality and energy are factors that will help overcome sloth-torpor.

Also, don't lay down when you are meditating and experiencing sloth-torpor or you will probably fall asleep. If you need to, get up and practice walking meditation . . . or splash water on your face.