  Bipartite quantum systems from the chiral universality classes admit
topologically protected zero modes at point defects. However, in
two-dimensional systems these states can be difficult to separate from
compacton-like localized states that arise from flat bands, formed if the two
sublattices support a different number of sites within a unit cell. Here we
identify a natural reduction of chiral symmetry, obtained by coupling sites on
the majority sublattice, which gives rise to spectrally isolated point-defect
states, topologically characterized as zero modes supported by the
complementary minority sublattice. We observe these states in a microwave
realization of a dimerized Lieb lattice with next-nearest neighbour coupling,
and also demonstrate topological mode selection via sublattice-staggered
absorption.
