In the presence of a 4Ï€-periodic contribution to the current phase
relation, for example in topological Josephson junctions, odd Shapiro steps are
expected to be missing. While missing odd Shapiro steps have been observed in
several material systems and interpreted in the context of topological
superconductivity, they have also been observed in topologically trivial
junctions. Here, we study the evolution of such trivial missing odd Shapiro
steps in Al-InAs junctions in the presence of an in-plane magnetic field
Bθ. We find that the odd steps reappear at a crossover Bθ
value, exhibiting an in-plane field angle anisotropy that depends on spin-orbit
coupling effects. We interpret this behavior by theoretically analyzing the
Andreev bound state spectrum and the transitions induced by the non-adiabatic
dynamics of the junction. Our results highlight the complex phenomenology of
missing Shapiro steps and the underlying current phase relations in planar
Josephson junctions designed to realize Majorana states