Why can't I find the related NEWT disseminated message for all disseminated messages?

Ported In Messages

When a trade is ported-in, the port-in message is not disseminated. Only the original SDR has the originally ticked messages available. As such, when an update is made to the trade that qualifies for public dissemination. KOR will tick that message and the Original Dissemination Identifier will only ever reference the first ticked message by KOR and not a NEWT and the field [Ported In Message Update] will be true. 

Trades executed over a year ago

The SDR's public reports on ticked data are only required to be made available for a year.