Photos on Mac not importing with correct EXIF date

Matti Haveri is pretty much the Exif expert, but it might help if you told us what OS you are using. Like him, I've not seen this, before. But different apps seems to use different descriptors for fields. I see that the app ExifTool Reader uses "Date/Time Original" for the what GraphicConverter call the Create Date. As you know, Photos should be picking up Create Date and using that, as it works for me.

Have you done the usual routines for computer glitches like

• Restart the computer (of course)
• Re-start in Safe Mode. This bypasses certain potentially disruptive processes. Safe Mode is different for different computers, so see this: 

      Start up your Mac in safe mode - Apple Support 

• Use another library if you have one, or make a small test Library with a few pictures in it and see if the the crazy import date still happens. You can create a new Library by closing Photos and then option-clicking on the Photos icon.
• Make a new user and see if the same problem recurs with it.

The idea is to find out if the problem is with the Library, with your account, or with caches and login items, and stuff like that. One of these steps may fix the problem, but their failure to work also helps figure out what's happening.

In any case, you don't have to change 700 pictures one at a time. I know from his posts that Matti and I both use the app GraphicConverter ($40)  to batch copy Exif Date data from one field to another. There are other apps listed at the App Store and through a Google search that will do the same, but aren't as comprehensive (or as expensive) as GraphicConverter. It can be fast...

different apps seems to use different descriptors for fields. I see that the app ExifTool Reader uses "Date/Time Original" for the what GraphicConverter call the Create Date.

GraphicConverter's ExifTool tab displays the exiftool default view for the tags. exiftool displays about the same output as GraphicConverter without any additional options (here G2 group filter '-Time:All' is used to display only time-related tags. I deleted unimportant macOS filesystem dates like FileModifyDate from the output below although they are a source of much confusion in this forum):

exiftool -Time:All image.jpg
Modify Date                     : 2001:06:01 12:00:00
Date/Time Original              : 2001:06:01 12:00:00
Create Date                     : 2001:06:01 12:00:00

I always use the view below with '-a -G1 -s' options because it:

-a shows possible duplicate tags (see below how many more tags are now displayed). Often there is a same name tag (DateTimeOriginal) in a different group (ExifIFD and XMP-exif) and sometimes some app might grab a wrong date from a wrong group.

-G1 what group (ExifIFD, XMP-exif etc) they belong. Try G0, G2, G3, G5, G6, G7, G1:7 for different view options. For example, G1 reports IFD0:ModifyDate, G0 reports EXIF:ModifyDate, and G2 reports Time:ModifyDate for the same tag's group.

-s actual tag names that are used to write the tags. I.e. 'DateTimeOriginal' instead 'Date/Time Original'.

exiftool -a -G1 -s -Time:All image.jpg
[IFD0]          ModifyDate                      : 2001:06:01 12:00:00
[ExifIFD]       DateTimeOriginal                : 2001:06:01 12:00:00
[ExifIFD]       CreateDate                      : 2001:06:01 12:00:00
[XMP-exif]      DateTimeOriginal                : 2001:06:01 12:00:00-05:00
[XMP-xmp]       CreateDate                      : 2001:06:01 12:00:00-05:00
[XMP-xmp]       ModifyDate                      : 2001:06:01 12:00:00-05:00

The following EXIF date tags are in practice always set to the same time:

ExifIFD:DateTimeOriginal is the date/time when original image was created. This is the most important date tag for images (movies use other tags).

ExifIFD:CreateDate. Called DateTimeDigitized by the EXIF spec is the date/time the digital file was created.

IFD0:ModifyDate. Called DateTime by the EXIF spec is supposed to be changed whenever the image is modified but in practice that is not done.

importing photos from finder into Apple Photos. The photos have the correct date they were taken under the "EXIF" tab under "Date Time Digitised" and "Date Time Original".

Sounds weird. I presume you look at Preview.app Inspector which reports the most important image date 'ExifIFD:DateTimeOriginal' as 'Date Time Original'. On the other hand, Finder > View > Show Preview reports it as 'Content created' (I wish Apple would be consistent when reporting these tags).

So Photos.app should grab the date from it. Unless there is already a file that Photos regards as a duplicate (I guess it should report that, though). Or if the image metadata is corrupted and Photos.app grabs the date from some other metadata tag or reports the time as 0.00 (I have seen that) or as a last resort grabs it from the FileCreateDate, as seems to happen for you.

See also:

Movie dates and Photos.app - Apple Community

Is there an issue with my Photos library?

Where is it stored? Internal or external volume?