When you activate your medalion do you guys see some glowing bags? One example is in the Nekker cave in Flotsom. Even though they're glowing it seems like you cant get any items from them. Is it a glitch or do they serve some other function? (like maybe they're flammable or something)

There are several instances of this through the game. Some containers glow but cannot be interacted with (or they're out of reach). Not sure if it's a glitch or if they just intentionally placed models there with the same reference as other interactables.

Those things glowing in the Flotsam nekker cave are not bags, but stains of blood on the ground that you can interact with.

Not only containers glow. You can see it better a bit later in the game, when you'll have to follow a blood trail on the ground.

Actually there are literally sacks that do glow in the Nekker cave. They're scattered around the walls before you first fight that huge horde of Nekkers.

And there are containers scattered around that follow that behavior. It's a bit annoying, but I've just learned to ignore the ones I can't get.

I can affirm to this. Glowing bags, with no blood or doors or other "interact-ables" items around. Generally they are found against a wall or in a corner.

I have also on occasion noticed specific large rocks in forests that are glowing. The glow envelops just the rocks, and not their surroundings, so it is quite clear. Again, there is no sign of any blood, that may have caused the glowing.