My spouse have the same issue. We made a day trip to USA... in the CBSE report is missing entry back into Canada!
I emailed the CBSE contact on the report. No reply...
During my recent re-entry to canada. I asked the CBSE officer that my spouse report is missing entries. The office said, they can't do anything and simply said the Officer would have missed to scan the passport/PR card. He also advise to clarify this during the Citizenship Interview, if asked...!!
Since, Myself and my spouse re-entered on same day. I have the details on my CBSE report details related to time, Office Name, Gate# etc., So I'm going to write a letter with all details and Also attach the email I sent to CBSE on the missing entry... If the Citizenship office asks for details, my spouse will be giving this letter... That's the best I can think off.
My spouse has test & interview on 1 Sep.
if you find more details keep me posted! All the best!