  We point out that the $\text{USp}$ symmetry associated to a full twisted
puncture of a class S theory of type $A_\text{even}$ has the global anomaly
associated to $\pi_4(\text{USp})=\mathbb{Z}_2$. We discuss manifestations of
this fact in the context of the superconformal field theory $R_{2,2N}$
introduced by Chacaltana, Distler and Trimm. For example, we find that this
theory can be thought of as a natural ultraviolet completion of an
infrared-free $\text{SO}(2N+1)$ gauge theory with $2N$ flavors, whose
$\text{USp}(4N)$ symmetry clearly has the global anomaly.
