Jungle needs to have a catch up mechanic, full stop.
There is literally no way for jungle to be viable below Challenger unless it's given a catch up mechanic. If one of your lanes is losing, you're completely removed from the game as the fed laner and jungle permanently invade you.
The same applies to the enemy jungle getting fed. If they get a couple of early kills and their lanes aren't losing, they can just permanently invade you. Most times this happens, it's not even because they did anything particularly well, but more likely that they just cleaned up on a dive or two.
You can maintain vision and avoid them when they invade, but because there's no catch up mechanic, you have no way to get back in the game. Every conceded camp/scuttle/buff puts you permanently further behind.
This needs to be fixed.