Attempts to be mindful, ala mindfulness practices, are certainly at odds with "aha" creative experiences as these emerge out of a wandering mind:
Mind wandering “Ahas” versus mindful reasoning: alternative routes to creative solutions
So, should one strive to be mindful, or should one allow it to unfold naturally, as a result of meditation, alternated with activity?
As this Soto Zen master says: Stop being mindful!
As Maharishi Mahesh Yogi said:
The two steps of progress are rest (TM aka dhyana) and activity (everything else found during waking, dreaming and sleeping).
An enlightened person, at least in the beginning stage, is where the qualities of rest (meditation) have spontaneously emerged and become permanent in the middle of all possible activity (waking, dreaming and sleeping).
One doesn't cultivate this by attempting to BE mindful, but simply by allowing the natural cycle of rest and activity to proceed.
And mind-wandering is the essential basis of dyana and the spontaneous ability to switch from paying attention TO something and switching attention (via mind-wandering) to something else IS the creative process. In enlightenment mind-wandering is always present, even when one is fully focused on some thing, and so creativity is always present as well.
Mindfulness, in this situation, merely refers to the ever-present observer, always observing. Such a person is always mindful because it is impossible for the ever-present observer to NOT be mindful.
This confusion is why people worry that BUddhism detracts from creativity. It isn't Buddhism that detracts, but inappropriate attempts to practice what spontaneously emerges from practice: being always mindful.
The "description" that one is always mindful when one is enlightened has become a "method" to use to become enlightened.
This can only take one further away from enlightenment, which is where one is always creative because the mind is always free to wander.