Why is this happening so much recently?

Hey guys!

So in 3 of my recent games I've noticed something happening that I've not seen before, but it's turned out poorly in every instance.

"Lane truce" is what these people have been calling it. Simply put, anyone in the lane decides not to fight and only focus on farming. The people in lane will all chat "run" whenever the jungler is nearby. And as a jungler, I can't go to that lane because it's a waste of time.

In the first game, it was mid lane. The enemy fizz got to free farm against our Gragas, and eventually "ended" the truce along with our team

The second game was an enemy Nasus with a friendly Illaoi. Needless to say that a 20 minute 600 stacked Nasus isn't fun.

I didn't report anyone because everyone involved was actually a good person, even though one game was ranked (the Nasus one obviously).

My question is: Why is this happening all of the sudden? And what are the other people in the game supposed to do to react?