[BUG] Bug when unarchiving certain projects

Some projects get stuck in the "Archived / Unarchiving" state, as reported by different users:
 
"Projects seem stuck with the “Unarchiving project...” message for hours. On the projects page, from the status, it has the symbol of unarchived but it is written “Unarchiving”.

This happens somewhat randomly so we need to understand the cause for fixing it.