What is the ruling on intentionally swallowing something tasteless that enters the mouth and is swallowed during the day in Ramadan, even though it is not visible to the eye?

If a fasting person intentionally swallows anything that reaches their stomach, their fast is invalidated, whether it is something commonly eaten or not, even if it is a very small amount like a sesame seed. However, if something enters the stomach unintentionally, such as a fly entering their throat, their fast is not invalidated by that. One should not pay attention to the whispers of something entering the throat unless it is confirmed that it was intentionally swallowed.