Watery slush at the spout usually means the batch is not done, the mix is short on sugar, or you are on the wrong setting. Separation in the cup, ice crystals splitting from liquid, points at low sugar or carbonation. Slush with enough sugar in it holds together; that is what the 8 to 15% range is for.
The first pour can look done while the core of the batch is still loose. High-sugar and alcoholic mixes take 45 to 75 minutes. Give it longer before adjusting the recipe.
Alcoholic mixes on the regular Slush setting behave badly. Use Spiked Slush (or the Frozen Cocktail mode on machines that have it) and, if your model allows it, turn the temperature colder rather than adding more sugar.
A mix right at the 4% sugar floor makes coarse, wet slush that splits fast in the glass. Richer mixes (8 to 15% sugar, or with body from juice pulp, cream of coconut, or condensed milk) pour thick and stay uniform.
Low sugar makes coarse slush that melts and splits quickly. Move the recipe toward the 8 to 15% sugar range or add body with juice or cream-based ingredients.
Spiked Slush or Frozen Cocktail mode, with the temperature turned colder. Adding sugar to an already-sweet cocktail is usually the wrong fix.
Real coconut cream clumps in cold mixes. Dilute it with warm water and blend it smooth before it goes in the vessel, not after.