The reversibility of the martensitic phase transformation is crucial for the functionality of shape memory alloys. The easier the martensite is pinned, the faster occurs the degradation of the shape memory effect during cyclic loading. To shed some light on to the understanding of degradation, this study investigates explicitly a single-crystal of the FeNiCoAlTi system with a non-favourite crystallographic orientation for superelasticity resulting in a poor reversibility of the stress-induced martensitic phase transformation. Two complementary in situ characterization methods – digital image correlation and acoustic emission – are used to characterize the evolution of the martensitic phase transformation and the role of dislocations during deformation. Whereas the digital image correlation is applied as a full-field method to evaluate two-dimensional strain fields on the surface of the gauge length of the single crystal, the acoustic emission measurements provide volume integrated information with a temporal resolution in the range of microseconds. Thereby, experimental evidence was elaborated pointing at mechanisms that so far have been underrated in terms of functional degradation. Detwinning, associated with high acoustic energy, is identified as a significant factor contributing to poor reversibility. Additionally, high-resolution electron backscatter diffraction measurements were firstly utilized to identify residual stresses in the austenitic matrix, which significantly contribute to the reverse transformation. Micro-mechanical experiments using pillar compression tests were carried out to study the influence of residual back stresses of the austenitic matrix on the reversibility of the martensitic phase transformation. A reduced reversibility was found in the case of the absence of back stresses. The findings from this study foster the understanding of pinning mechanisms during loading of the FeNiCoAlTi shape memory alloy eventually enabling targeted optimization for enhanced superelastic material behavior.