Use only liquids permitted by the exact dispenser instructions. A reservoir intended for drinking water should not be assumed suitable for sugary, acidic or milk-based drinks.
What the observation tells you
Those liquids can leave residues in narrow passages and create cleaning or material-compatibility problems. The fact that a drink fits through the filling hole says nothing about whether the valve and seals were designed for it. Dilution does not establish suitability.
A useful next step
Check the manual before filling. If an unsuitable drink has been used, stop and follow the manufacturer's cleaning advice rather than flushing with chemicals or dismantling concealed dispenser parts.
Manuals and supporting guidance
Model-specific instructions take priority. These references support the practical principles discussed here; they do not diagnose your appliance.