I knew that was the case prior to the built-in mod loader but wasn't sure if that had changed since. I just did some testing and noticed that deactivating the mod within the mod loader prepends an underscore and activating it removes it.
Lich_Knight123 I just downloaded the Oneiros mod and got the same message, but I activated it and the mod loads fine, I ran it with the debug log and didn't get any errors. I was able to get the dream sequences just fine. I don't think you'll have any issue playing it.
I did a quick scan through the MGD discord and somebody else reported that bug but I don't think a fix was ever issued.