Date changes with metadata write-back

[cg]

I wrote a similar post about this problem with video files, but I'm also noticing it with image files.

As I process batches of my images, many of them lose their Date Subject Modified metadata when I write back metadata, even if that date hasn't changed. For instance, I adding people annotations, which I confirmed only set the PersonInImage tag to write back when I mouse-over the yellow pen on the thumbnail. Of 358 images I wrote back, about 70 lost their date when read back in.

I can usually fix them by running TimeWiz, setting the date to the "File Last Modified" variable. But for some of them, that date has changed as well to the current date.

How would I begin to diagnose what's happening here so I can either modify my configuration or my workflow so I don't keep having images move around the timeline?

Thanks!

[Mario]

We've discussed this in another thread just two days ago. The reason is always the same, and it has been explained in detail in the
How IMatch uses Date and Time Information
help topic - especially this section: https://www.photools.com/help/imatch/#tech_exifdate.htm?dl=h-5

Your files don't contain any usable timetamp.
IMatch falls back back to the "last modified time" reported by Windows.
This changes of course when you write-back, causing the timestamps to change again.

1. Go to Edit > Preferences > Metadata 2 and set XMP Import: Mark file as pending write-back to Yes.

2. Either actually set a date created and date subject created in the Metadata Panel or click the pen in front of the two timestamps to mark them as modified.
This ensures that IMatch writes back the timestamps into XMP and then they stay forever.

Changing the setting in 1 means that IMatch from now on automatically makes the two timestamps pending when you import new files and IMatch sets these timestamps.