Cannot load Bloodmoon without Tribunal
The content file selector hallucinates a dependency on Tribunal.esm for Bloodmoon.esm. This is desirable behaviour in the sense that it prevents people from loading the expansions in the wrong order (i.e. it forced Bloodmoon to load after Tribunal.) However, it also makes it impossible to select just Bloodmoon.esm as checking it will automatically check Tribunal.esm.
Pretty minor issue for the launcher since people are likely to be running mods that require both anyway, but the editor not allowing you to create a mod that only depends on Morrowind.esm and Bloodmoon.esm isn't great.