For improving efficiency and productivity companies are used to work with workflows that allow them to manage the tasks and steps of business processes. Furthermore, modalities have been designed to allow loose specifications by indicating whether activities are necessary or admissible. This paper aims at verifying modal specifications of coloured workflows with data assigned to the tokens and modified by transitions. To this end, executions of coloured workflow nets are modelled using constraint systems, and constraint solving is used to verify modal specifications specifying necessary or admissible behaviours. An implementation supporting the proposed approach and promising experimental results on an issue tracking system constitute a practical contribution.