Some Calgary applicants mentioned that after their tests, the oath officers told them that there is a huge backlog for oath invitations. So that might be the case currently. Hopefully it eases.
But if you check the spreadsheet, you will notice that Calgary and Edmonton, especially Calgary always sends out test invitations the fastest and has the highest completion rate of applications within 7 months of application regardless of if they sent out AORs or in processes late. So don't worry, I have hope that they will pick up soon.