If I were you, there were a few things that I would do (but only my two cents)
- Go to this website
https://services3.cic.gc.ca/ecas/security.do, use your UCI (Unique client identifier) to check if an AOR has ever been issued on your citizenship application. UCI is the Id No on your PR card if you don't know. If the citizenship application has been issued AOR or in process, the results will be returned.
- If nothing returned from ECAS, call IRCC one more time to have the
latest update on the application if an AOR has ever been issued or if your application has been returned?
- If ECAS didn't show anything, and no luck in getting helpful information from IRCC, I would just submit a new application with an explanation letter.