Ranked Position Promo Bug

Not sure if this is a bug or not, but I had 100 LP for my bottom position but never showed I was in promos not sure if this was due to it being only able to be in promos for a single position as I am still in my promos for my Jungle position. I lost a game playing bottom which it showed my LP as 100 and dropped my points based on a loss. I believe the position ranking system should have been further looked into before rolling it out as it seems even if you get 100 LP points in any positon you still have to win multiple games just to be eligible for a promotion.