As you can see from the pictures, we have some sort of shadow/light problem on my private server. It happens to everyone when we try to do some terraforming. We've tested it and it seems like all players are seeing the same shadows, so I assume it starts for everyone at the same time, but we haven't been able to confirm that yet. This means that if I break blocks and a friend of mine walks over, they will see the same bug as me.

Also, there is no trigger I can find for when it happens, we would play for 1-2 hours and then it would start or just 10 minutes. In the pictures, I've removed some dirt, but the shadows of the removed blocks don't go away, and even any kind of light emitting objects are ignored, only the block under the lights is lit. This is a pretty big problem because mobs spawn even though you think you have torches everywhere, but the light engine just refuses to update. The light overlay won't show any updates when this problem occurs.

Reconnecting to the server restores the lighting to the way it should be. And as far as we can tell, it seems to be all over the place, not just 1 chunk. It is also visible without shaders. Reloading chunks and shaders does nothing either. I also tried enabling Forge Experimental Lighting which did nothing.

We're on the latest version of ATM 9, I haven't changed any configs or anything for both the clients and server.