Does the use of black musk, whose scent is felt in the throat, invalidate the fast, especially with attempts to expel it and uncertainty about its reaching the stomach cavity?

The basic principle is that pleasant scents, like musk, do not invalidate the fast. This is unlike frankincense (bakhoor), which has particles that can reach the throat. Jurists have explicitly stated that musk does not break the fast, even if inhaled, because it has no substance. However, if musk is used as an incense and its smoke reaches the throat, then there is a difference of opinion among jurists regarding whether it invalidates the fast or not. The more cautious approach is to avoid it and make up for the days when it reached the throat.