The Auger Muon and Infill Ground Array (AMIGA) is a muon detector that is currently being built as part of AugerPrime, the upgrade of the Pierre Auger Observatory. It consists of 30 m$^2$ plastic scintillator counters buried 2.3 m underground and water-Cherenkov detectors at the surface, organized in a periodic 750 m triangular array, and deployed over an area of 23.5 km$^2$. Each counter is composed of three 10 m$^2$ modules segmented into 64 scintillator strips. Two positions of the engineering array were further equipped with "twin" detectors to assess reconstruction uncertainties. AMIGA allows for direct measurement of the muon content of air showers with primary energies above 10$^{17}$ eV. In this work, the detector reconstruction strategy is revisited and the bias induced by particles traversing two adjacent strips, the so-called corner-clipping effect, is thoroughly analyzed. A bias correction based on end-to-end simulations of both the air showers and the detector response is presented. The improved reconstruction method was applied to experimental data acquired by the AMIGA engineering array, and preliminary results of the muon content estimator $\rho_{450}$ (muon density 450 m from the shower axis) are presented.