Camera Raw writes your JPEG files back out with updated metadata no matter what settings you choose, because Adobe feels they understand the format of metadata in the files well enough to be confident they will not corrupt the files.
I've asked them for years to avoid doing that, to no avail. I don't want my original files re-written. It sounds as though you are of a like mind.
It is for this reason that I *never* open a JPEG file through Camera Raw.
It's possible there is a time zone problem or something, but that's not the point. What, specifically, is corrupted is less important than Adobe believing it's okay to write back to your JPEG files. That you have actually seen something corrupted is testament to it not being unfounded paranoia.
Generally I'm supportive of Adobe's design decisions, but absolutely not on this issue. All I ask is that Adobe honor the "keep settings in the central database" preference choice for ALL input files, not just those for which they would otherwise write an XMP file. I don't think it's too much to ask.
By the way, you might want to visit the Camera Raw-specific forum and make note of your issue there:
Agreed and thanks!
I have many instances now where photos taken within minutes of each other appear to have been taken hours apart. So it appears that there is both a bug (time shift) and a poor design choice (write back) causing a really bad experience.
There also seems to be something similar going on in the lightroom catalog - many of my shots are 7 hour offset between the catalog and the file. Not sure exactly what made teh change but 8000 images were given an offset - both NEF and JPG file impacted.
I had to stop "writing metadata to files" after I discovered this. Fortunately I had a backup but it will take hours to fix the catalog. I could have just re-imported but that would have lost 100's of hours of tagging. Easier to fix the time offset.
I had to write a program & script to tell me which of the 23000 images had been messed with. Now to fix the catalog with endless "edit date/time" adjustments.... what a pain.
the file itself has the "Date Taken" time updated - 7 hours ahead of the original correct time.
How are you assessing this? (please send me a jpeg, with info: what the correct time should be, and what the (modified incorrectly) date-time is).
If you also have a reference (un-malflicted) jpeg to send, it would help to compare.
To be more specific: the question is: "is the exif:dateTimeOriginal tag being incorrectly re-written?" (it shouldn't be), or is the xmp:dateTimeOriginal tag being incorrectly written, and subsequently reported (my current theory).
Plugin note: if my theory is wrong, and the problem is the former (exif-tag itself being re-written), then MetaRep won't be able to fix the problem, *and* it represents a bigger bug in my mind, since writing xmp is more Adobe's perogative than altering exif tags (given that they will be updating even camera-original jpegs, and don't support sidecars for them - a related yet different issue...).