Upload one of the front-camera photos to Dropbox or similar and post the sharing link here. I'll take a detailed look at the photo's metadata to see what might be going wrong.
I have uploaded two photos here:
One is using the main camera (20180917_104549) and the other the selfie camera (20180917_104600.jpg). The file name is the date the photo was taken. You should be able to see that when imported into Lightroom the selfie camera photo has a different capture time to the file name.
I see the difference in capture times when they're imported into my LR 7.5. A quick examination with ExifTool doesn't show anything obviously wrong. Later today I'll look more closely under the microscope.
It took a bit of poking around -- the file 20180917_104600.jpg uses an invalid format for storing the capture date:
The EXIF standard requires ":" to separate year, month, and day, but the file uses "-" instead. It's a little weird that the back camera gets it right and the front camera gets it wrong -- you'd think they'd use the same exact code.
Some programs don't check for that, but obviously LR does. In general, LR and other Adobe products try to strictly follow the industry standards (which is a good thing). You should file a bug report with Samsung.
You can use the free (and very robust) Exiftool to fix the dates, using this command line:
exiftool -tagsfromfile @ -datetimeoriginal *.jpg
If you want to run this on photos already imported into LR, first select all of them and do Metadata > Save Metadata To File. Then run the Exiftool command line. Then do Metadata > Read Metadata From File. Or use the Capture Time To Exif plugin, which makes it easier to run Exiftool on imported photos.
Thank you for looking into that. I will try to report it to Samsung in that case then... although I imagine there is little chance they will see my report. I guess for now I will run the command you have written. Thanks again.
I did a quick Google for where to submit Samsung-specific bugs (which I'm pretty sure this is, not a generic Android bug), and didn't find any authoritative answer.
I've only now got round to trying to sort this problem out with my photos using the tool you suggested. When I run the command from your screenshot I don't get the same results as you do. Instead I get (these are different photos but with the same camera):
Luke$ exiftool -exif:datetimeoriginal *.jpg
Date/Time Original : 2018:08:16 22:33:37
Date/Time Original : 2018:08:16 22:33:51
Where the last three images are photos taken with the front facing camera. Do you know if this is an issue with the version of the tool I have, or if it is something else I'm doing wrong?
Thanks again, you've been a big help with this and I appreciate it.
EDIT: I think I have solved my own issue with regards to why there is no date specified. I had followed your instructions of selecting the option of saving the metadata to the file in Lightroom and it appears to have overwritten the original date that was in there. I restored to the original file and I am now able to see the dates. I will now attempt to use the tool to correct the date time to the exif standard format.
EDIT 2: When running the command on the original files (without having saved the metadata from Lightroom) the command to correct the exif data appears to work correctly. Thanks again for your help.
Glad you got it sorted.