Completed Courses Showing as Not Started within specialization

Summary:

We have a number of cases in which the specialization shows as 'In Progress' with 11/13 activities completed.

The courses within the specialization have been completed by the learner, and show as 'Completed' in their transcript, however within the specialization, the courses still show as 'Not Started'.

We've noticed that in each case the learner has 1 deleted record for the course and 1 completed record.

Both course/offering assignment types say voluntary.

We would expect that the specialisation should recognise that there is a completed record for the course and therefore the specialization should reflect this.

Does anyone know why this isn't the case in this scenario?