Numbers by side of projects in Omnifocus

I am assuming that the number by the side of projects in the projects list indicates the number of items with a due date, with the colour indicating that if they are near or overdue.

What i don’t understand is why i am getting a 1 in red by a project that is marked as complete, with every action within the project also marked as complete.

Am i missing something or have in encountered a bug ?

I think it’s a bug that I’ve encountered before. To the best of my recollection, rebuilding the database (File, Rebuild Database) sorted it.