These shiny spots being the "deepest" points in the reverse image of the die may have silver depositions/ deposits of small particles of silver build up on/in the "die" frosted areas during production run and prevent a 100% imprint thus leaving what appears to be a shiny missing metal spot. it does not appear to be a delamination of the parent metal prior the striking.
After a few or a hundred strikes following this strike the bits of deposited silver in the "die" could fall out and the die would produce 100% normal strikes again. similar things happened in the steel industry and required my investigation into what caused part failures.. ie customer wanted their money refunded.. I would have to approve or disprove their complaints.

DMR -- Damaged Material Report

Gabe