Non-Hermitian bipartite photonic lattices with charge-conjugation 𝒞𝒯 symmetry can support resonant defect modes which are resilient to bipartite losses and structural imperfections. When, however, a (self-)induced violation of the 𝒞𝒯-symmetry occurs via tiny permittivity variations, the resonant mode is exposed to the bipartite losses and it is destroyed. Consequently, the transmission peak is suppressed while the reflectance becomes (almost) unity. We propose the use of such photonic systems as power switches, limiters, and sensors.