Due to pressure to meet goals, some test-takers preparing for the IELTS (International English Language Testing System) Writing test solicit written feedback (WF) from an expert provider on their rehearsal essays, in order to identify and close gaps in performance. The extent self-directed candidates are able to utilize written feedback to enhance their language and writing skills in simulated Task 2 essays has yet to be investigated. The present study addresses one learner factor deemed prominent in mediating the learning potential of WF, student engagement. The study used assessments of student writing according to the public band descriptors and text-analytic descriptions from three Task 2 rehearsal essays triangulated with five rounds of semi-structured interviews to explore how four learners preparing for IELTS Writing engaged affectively, behaviorally, and cognitively with asynchronous, electronic written feedback provided using the "Kaizena" app. The study found that, while the learners highly valued WF, they were not always able to understand the intentions behind comments or envisage an appropriate response, leading to negative emotional reactions from two learners in the form of anxiety and frustration. Written progress across the essays was limited, stemming from an initial lack of buy-in to making content revisions and surface-level approaches to WF processing. Moderate behavioral engagement with indirect error treatment was exhibited, although meaningful accuracy gains were apparent for only one learner and content changes meant many errors went uncorrected. The implications for practitioners of IELTS Writing preparation are discussed.