Thanks for the info.
As I have stated all pages sit under single parent (/trips) and as you can see from the screenshot below for another product (River Kwai Mini Adeventure) the PL was set around the same time 13 Dec 2017.
This is pretty much identical for all our products and the subsecquent lookup info are all same as the site went through HTTP to HTTPS and Design File updates during the past 1 year. So all products has the same look up record.
If the PL was set explicitly set, the lookup record pattern would be different for Mekong but this is not the case. In addition there are only 3 people including myself only has admin acess and any big changes such as Design File, PL or any product layout change has to go through approval process, therefore explicit change like this never happens. Also it is not just this product that didn’t get the new PL, there were roughly 15-20 products from 120 that didn’t get the new PL.
Unforteunaly I don’t have access to the database.