$a_0(980)$ external products, develops a singularity at 1420 MeV, which is seen as a peak for $\pi f_0(980)$ or $\pi a_0(980)$ production. This was already suggested in Ref. [@Liu:2015taa] and shown explicitly in Refs. [@Ketzer:2015tqa; @Aceti:2016yeb], and provided a natural explanation of the COMPASS observation [@Adolph:2015pws] of a peak in the $\pi f_0(980)$ mode around 1420 MeV, which was interpreted as a new resonance, the “$a_1(1420)$” in Ref. [@Adolph:2015pws]. In Refs. [@Ketzer:2015tqa; @Aceti:2016yeb] the peak was interpreted as a consequence of a triangle singularity associated to the decay mode of the $a_1(1260)$ into $K^* \bar K$, followed by $K^* \to K \pi$ and fusion of the $K \bar K$ to give the $f_0(980)$. The mechanism to produce the $\pi a_0(980)$ from the decay of the $f_1(1285)$ is identical to the one used in Ref. [@Aceti:2016yeb] to produce the $\pi f_0(980)$ from the decay of the $a_1(1260)$. Only the isospin combinations are different, but the singularity is tied to the masses of the particles and is independent of the internal degrees of freedom like the isospin. We shall see that, also in this case, a peak is produced around 1420 MeV in the $\pi a_0(980)$ decay mode of the $f_1(1285)$ which 