We present a novel scenario in heavy-ion collisions where different modes of
collective motions evolve asynchronously in the created nuclear medium. Such
physics mechanisms could each dominate at a distinct evolution stage, or
coexist simultaneously without coordinating with each other. If we employ a
separate single-harmonic Fourier expansion to describe how each asynchronous
collective motion affects particle emission, the particle azimuthal
distribution should be the product of all these expansions. Consequently, cross
terms between collectivity modes appear, and their contributions to
experimental observables could be significant. In particular, we argue that the
chiral magnetic effect (CME) and elliptic flow can develop asynchronously, with
their convolution affecting the observable that is sensitive to the
shear-induced CME. We will use the event-by-event anomalous-viscous fluid
dynamics model to illustrate the effects of this scenario. Besides giving new
insights into searches for the CME, we also propose a feasible experimental
test based on conventional flow harmonics