I've seen instances where minor non-conformances have occurred due to circumstances that are unique/isolated/unusual situations. The QA Manager decided that a CAPA was not needed. The non-conformance was simply documented, along with the root cause, the reason that the root cause was isolated and not likely to recur, and the resolution for the particular instance of non-conformance. The QA Manager signed off explicitly that a CAPA was not required for the situation.
Note: The QA Manager only did this for very minor non-conformances. However, you were looking for instances where CAPAs were not issued, so these are instances that I have seen.
IMNSHO, the best way to address this type of thing is before it happens, in your SOPs and reporting forms. The SOP should explicitly identify conditions where a CAPA may not be required, and should identify what explanations and sign-offs are needed when choosing not to issue a CAPA. Any forms used to document non-conformances should include a check-off for whether a CAPA was issued, and if not, should include a fillable field for the explanation for not issuing the CAPA.