Same happened to me, another player told me to reconnect and it was fixed.
Steps leading to bug:
- Got dc'd from pre-game lobby
- Attempted to reconnect to lobby, got disconnection prompt
- Finally able to reconnect after many attempts & logging out/in once (the load screen started for everyone else most likely)
- Connected into the game same time as other players (game clock under 0:12)
- Could not walk past the blue barrier lines after they had gone away at the 15 second mark
- Reconnected and problem fixed
This bug caused me to be nearly 2 lvls behind, lets just say my laning phase was rather unpleasant.