There is a long-standing anomaly in the ratio of the decay width for $$\psi (3770)\rightarrow D^0\overline{D^0}$$ $\psi \left(3770\right)\to D^0\overline{D^0}$ to that for $$\psi (3770)\rightarrow D^+D^-$$ $\psi \left(3770\right)\to D^{+}{D}^{-}$ at the level of $$9.5\,\sigma $$ $9.5\sigma$ . A similar anomaly exists for the ratio of $$\phi (1020)\rightarrow K_\text {L}^0K_\text {S}^0$$ $\varphi \left(1020\right)\to K_{\text{L}}^0{K}_{\text{S}}^0$ to $$\phi (1020)\rightarrow K^+K^-$$ $\varphi \left(1020\right)\to K^{+}{K}^{-}$ at $$2.1\,\sigma $$ $2.1\sigma$ . In this study, we reassess the anomaly through the lens of a Gaussian wave-packet formalism. Our comprehensive calculations include the localization of the overlap of the wave packets near the mass thresholds and the composite nature of the initial-state vector mesons. The results align within a $$\sim 1 \sigma $$ $\sim 1\sigma$ confidence level with the Particle Data Group’s central values for a physically reasonable value of the form-factor parameter, indicating a resolution to these anomalies. We also check the deviation of a wave-packet resonance from the Briet–Wigner shape and find that wide ranges of the wave-packet size are consistent with the experimental data.