Reconnected but still lost LP from a victory.

I disconnected for around 10mins from a storm but I reconnected and went from level 5 to level 11, got alot of assists and did my best to pull my weight even though my team was doing amazing for a 4v5. My issue is that I lost LP even though I reconnected and contributed? Is this a new feature or a bug? Was also duoing with Quinn, kept him up to date with the outage and my reconnecting, told him to tell the team my situation as well so they're not confused. This is a very irritating experience, I also helped get firstblood before I got disconnected!