There are areas/holes that take a long time to render in when joining the world or entering area

When loading in the world or entering an area there are areas/holes that take a long time to render in. They're not always in the same places. It won't allow you to walk into them or place stuff there and if you fly into them you can get stuck and start suffocating. If you look into them you can see outside and caves/tunnels underneath etc. Been happening for a long time now