Less lp?

I won a game with 20 lp right, and I go into post game screen to find a "couldn't retreave data" error. So I logged out and logged back in after I pressed the skip waiting for stats and only to come back that I only gained 10 lp, leaving me at 30, when in reality I should've left with 38-40 lp at the end of the day. Please fix and maybe give me the extra lp that was lost. And I didn't gain any lp or champion points after either.