showing that the $K^* \bar K$ peak associated to the $f_1(1420)$ is the manifestation of the $K \bar K^* + \mathrm{c.c.}$ decay mode of the $f_1(1285)$. On the other hand, the broad peak for $\pi a_0(980)$ decay in the region of 1400 MeV will be explained as a consequence of a triangle singularity, due to $f_1(1285) \to K^* \bar K ,~ K^* \to \pi K,~ K \bar K \to a_0(980)$. The $K^* \bar K$ decay mode of the $f_1(1285)$ appears as “not seen” in the PDG [@PDG]. Indeed the $f_1(1285)$ is 100 MeV below the $K^* \bar K$ threshold. However, the $K \bar K \pi$ mode is reported with a branching fraction of 9%. These features found an adequate answer in several works [@Aceti:2015zva; @Aceti:2015pma], where the $f_1(1285)$ was considered as a dynamically generated resonance. This state, together with all the low-lying axial vector resonances, were obtained in Refs. [@Lutz:2003fm; @Roca:2005nm] as dynamically generated states from the interaction of pseudoscalar mesons with vector mesons, using a coupled channels unitary scheme with chiral dynamics for the meson interaction [@Birse:1996hd]. In the particular case of the $f_1(1285)$, the $K \bar K^* + \mathrm{c.c.}$ is the single channel in the coupled channel approach 