Latest ALICE results on coherent $\mathrm J/\psi$ photoproduction in ultra-peripheral Pb$-$Pb collisions at the LHC

The high flux of photons from lead ions at the LHC allows us to study photon-induced reactions in ultra-peripheral collisions (UPC) of Pb$-$Pb nuclei in a new kinematic regime. The study of these collisions, where projectiles do not overlap and hence hadronic interactions are suppressed, provides information about the initial state of nuclei. Coherent charmonium photoproduction is of particular interest since it is sensitive to poorly known gluon shadowing effects in target Pb ions. The newest ALICE results on vector meson photoproduction in UPC Pb$-$Pb collisions from LHC Run 2 are presented and are compared to current models describing nuclear gluon shadowing.