When I saw a flare on the ground, I decided to light it, but nothing happened. I thought it was just de-sync, so I decided to right click the flare on the vicinity. It didn't say anything about lag or desync, but just the "Pick up Road Flare", indicating it was lit, but no fire or light was coming out of it.

I took the flare in my hand and the fire + the light appeared and it worked if I placed it on the ground.

But I put it in my inventory and the light effect disappeared. I then tried to lit the flare again, but nothing happened. Not even if I put it in my hand.

Also the chemlights are either broken the same way as the flare, or I just can't see the light.