For many customers SprintR is chosen as the Agile/Scrum tooling for developing Mendix apps (mostly because of the integrated feedback loop and/or integral user story development in the Mendix modeler). SprintR though, has multiple known issues, which prevent it to be an embraced and effective agile/scrum tool.
Professionalising SprintR or partner up with a professional Agile/Scrum tool (like for instance Jira), will give a boost to the interaction between the customer and the development team and will smoothen release management of Mendix apps.