I don't see this. Maybe I don't understand it though.
Are you showing the right column for the date? There are plenty to choose from.
I have found a PDF file, based on its content, that sits in a zip file. It shows various dates. If I show the Date Modified column the information is the same as it appears in the zip itself.
In general, I find that X1 is a pig when it comes to all those columns. The "hard wired" searches are a mess. The Everything searches come with all sorts of extraneous junk? Do I need to know the "duration" of a file? (That column comes from a "Meeting" entry.)
I have spent some of this afternoon weeding out rubbish. You might find it fruitful to investigate the columns and to find the ones that work for you and do what you want.