While there is a growing body of research on affordances and benefits of integrating augmented reality (AR) technology in education, barriers to engagement (often misinterpreted as negative results) can sometimes be overlooked and unpublished. Based on observation and reflections on 6 conducted classroom sessions, together with the interview feedback from 32 pupils and 6 teachers, this paper summarises the main issues and barriers to implementation and engagement with AR tools in four primary schools. During the semi-structured interviews, participants have discussed several aspects of activity design, practical organisation details and their own skills and attitudes in relation to success, engagement and enjoyment with the activity. Results from thematic analysis summarise reported experiences into technical, practical and individual barriers. Learning from AR design development is a valuable process and sharing notable feedback and improvements can impact the speed and quality of future projects. For that reason, this article ends with recommendations and solutions for future research and educational practice.