Custom dimension sky/fog does not work

So I am making a mod that adds multiple different dimensions, each with their own sky colour. The first dimension has dense fog enabled and a grey sky, which worked as intended until I added a second dimension. Now the first dimension's sky is just the default overworld sky while the second dimension works as it was set up to. This is really confusing so any help would be much appreciated. 

Here are images of the dimension with and without a second dimension added: https://photos.app.goo.gl/ER8k5GjiyEVWiMuH6