Thoughts and feelings constantly appear and then disappear, sometimes never to be seen or captured again. This is the magical world of mind and emotion, where things emerge out of the vast world of the unconscious, and vanish again. Therefore suggests one is losing awareness of something. Person, animal who vanishes: love for someone which has gone; something we realised or learnt which we have lost sight of; an autonomous pan of self which we cannot yet direct. See autonomous complex. ... A Guide to Dreams and Sleep Experiences
One of the most annoying things about dreams is that images will vanish unexpectedly.
The mind has a great capacity for ‘magic’; to dream of things vanishing, and then possibly reappearing, means that we have to work a little harder from a spiritual perspective to understand.... Dream Meanings of Versatile
Psychological / emotional perspective: Just as a child believes in the world of magic, so the dream state is one that at the time is totally believable. When images vanish in a dream, they will very often become more tangible in the waking state and available for interpretation.... Dream Meanings of Versatile
Material aspects: There is also the tendency for us to forget various parts of the dream on waking.
The reason is that the subject of the dream has not yet fully fixed itself in consciousness. Working with dreams on first waking can help to ‘fix’ the information our subconscious is attempting to give us.... Dream Meanings of Versatile