I just imported a jpg image with a Date Taken in 2012, a Date Modified in 2017, and a Date Created today (as it was a copy of a file, so created today). MC imported the Date Taken into the [Date] field correctly.
I then edited the [Date] field to be in 2015, then ran the right-click "Library Tools > Update Library (from tags)" function against it. Alas, the [Date] tag was not set back to the original date, and worse, the Date Modified of the files was changed to the current date and time. So something was written to the file, but it wasn't the Date Taken.
I just tried the delete files, delete record of it from the Removed Database, re-import file, and that didn't fix the Date Taken value.
So deleted the [Date] field in MC and ran the right-click "Library Tools > Update Library (from tags)" function again. This time it set the [Date] field to the Zero day MC uses, 30 Dec 1899. That value was written to tags in the file; the IPTC Date Created and the XML DateCreated. Very
I tried some other tricks, but nothing restored the correct Date Taken, even though the correct Date Taken is still shown in the Tag Dump are of the MC Tag Action Window. Check if it does for your files.
I find the Date Taken to be a sacrosanct piece of metadata, never to be overwritten. Maybe MC deliberately only reads that tag once, and won't write to it ever, for that very reason. I haven't imported any important images into MC so far because of issues like this. I would be interested in knowing what is going on
If you search the forum for posts by MusicHawk about IPTC tags you might find some better information. He has been pursuing image metadata issues. Certainly what is happening now doesn't seem logical.