GPS location imported from iPhone has wrong hemisphere

I've just discovered the same issue. What irks me is that while NeoFinder (a DAM on the Mac) and also ON1 RAW can both read the xmp file correctly Lightroom can't (both Desktop and Classic). The issue has been known for a number of years now and I don't understand why Adobe doesn't show any interest in addressing it. As for a work around, if you wish to keep both the keywords and gps data, and have ON1, before opening the files in LR, open them in ON1 and select 'Embed metadata' under the Photos tab. Once embedded in the file gps info shows correctly in LR along with any keywords. 

Not in case you have thousands of RAW files geotagged in Photos and want to move them to Lightroom... Then your only option is to export originals with XMP....

I don't know why your command line didn't work for me either. My only conjecture is that exiftool already added an E to the end of gpslongitude when it was missing. So it wouldn't append the correct W. For example, a texteditor shows that temp.xmp file has no direction at the end, just numbers:

     <exif:GPSLongitude>123.94116166999997</exif:GPSLongitude>

But when I run the following:

exiftool -xmp-exif:gpslongitude test.xmp

What I get back has added an E:

GPS Longitude                   : 123 deg 56' 28.18" E

In any case, you have been incredibly generous and helpful, so thank you. I am still a newby, but I've learned a little bit now about what exiftool can do:-) And I wish that Apple would fix its bug!

Thanks for the helpful pointer! I wanted to be able to write back to say it had all worked, but it didn't....I started trying to figure out why--which got me more confused, and slowed me down.

The short answer appears to be: When I run exiftool on the image file (.heic), it gives the correct location. When I run it on the .xmp file that Photos 5.0 produces, it already has appended an (incorrect) "E" to the gpslongitude tag. That's presumably what Lightroom is also reading.

More confusingly to me, when I look at the .xmp file in a text editor, it looks different to me from what exiftool shows, in terms of GPS location.

My challenge is that I want Lightroom to import the keywords that are embedded in the .xmp file; otherwise, I would just throw away the .xmp file. One possibility would be to figure out how to get exiftool to copy the keywords from the .xmp files directly into the .heic files. Or else, I still need to figure out how to correct what's in the .xmp files. Both of those are beyond my exiftool skills, so advice would be very much appreciated.
 
Two example files are here. In a text editor, the (entire) .xmp file produced by Photos 5.0 looks like this:

<x:xmpmeta xmlns:x="adobe:ns:meta/" x:xmptk="XMP Core 5.4.0">
   <rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#">
      <rdf:Description rdf:about=""
            xmlns:dc="http://purl.org/dc/elements/1.1/"
            xmlns:exif="http://ns.adobe.com/exif/1.0/"
            xmlns:photoshop="http://ns.adobe.com/photoshop/1.0/">
         <dc:subject>
            <rdf:Seq>
               <rdf:li>Rockefeller Redwoods</rdf:li>
               <rdf:li>Favorites</rdf:li>
               <rdf:li>Redwoods</rdf:li>
            </rdf:Seq>
         </dc:subject>
         <exif:GPSSpeedRef>K</exif:GPSSpeedRef>
         <exif:GPSSpeed>0.023617127910090144</exif:GPSSpeed>
         <exif:GPSTimeStamp>2019-12-30T22:31:15Z</exif:GPSTimeStamp>
         <exif:GPSImgDirection>174.43260959</exif:GPSImgDirection>
         <exif:GPSLongitudeRef>W</exif:GPSLongitudeRef>
         <exif:GPSAltitudeRef>0</exif:GPSAltitudeRef>
         <exif:GPSLongitude>123.94116166999997</exif:GPSLongitude>
         <exif:GPSLatitude>40.341178329999991</exif:GPSLatitude>
         <exif:GPSLatitudeRef>N</exif:GPSLatitudeRef>
         <exif:GPSImgDirectionRef>T</exif:GPSImgDirectionRef>
         <exif:GPSAltitude>51.200000000000003</exif:GPSAltitude>
         <exif:GPSHPositioningError>32.004833106781454</exif:GPSHPositioningError>
         <photoshop:DateCreated>2019-12-30T14:31:15-08:00</photoshop:DateCreated>
      </rdf:Description>
   </rdf:RDF>
</x:xmpmeta>

Most notably, neither <exif:GPSLongitude> nor <exif:GPSLatitude> have a direction (N or E/W).

In exiftool, the key fields from exiftool *.xmp show (with incorrect East):

Subject                         : Favorites, Redwoods
GPS Longitude                   : 123 deg 56' 28.18" E
GPS Latitude                    : 40 deg 20' 28.24" N
GPS Latitude Ref                : North
GPS Longitude Ref               : East

In contrast, when I run exiftool *.heic, it shows (correctly)

GPS Latitude Ref                : North
GPS Longitude Ref               : West
GPS Latitude                    : 40 deg 20' 28.24" N
GPS Longitude                   : 123 deg 56' 28.18" W

So in short, the .heic file is fine. The .xmp file is not.

So if possible, how do I get exiftool to add the Subject/keyword fields to the .heic file? Or else, how do I correct the GPS coordinates in the .xmp files? (I have probably 20K of them in all.) I feel like it should be easy, but it's beyond me, so any help would be appreciated. (I can also post this in a exiftool forum if that's the preferred location).

Thanks so much--this is very helpful for a relative newbie like me. I feel like I've been wrestling with Photos and Lightroom for longer than I wanted, and a little advice goes a long way to helping me find a workflow that gets me where I am trying to go.

I think I figured it what's going on.

I have been exporting unmodified originals with the associated XMP file that contains the GPS info (in Apple's format, not the conventions) as well as keywords. When the XMP file is there, Lightroom gets the file keywords from the Photos app but gets the GPS location wrong.  In contrast, when the XMP file is NOT there, the GPS info is embedded in the exported Photos app picture, and Lightroom reads that info correctly. However, the keywords were in the XPM file, not in the photo, so without the XMP file, the keywords don't carry over. 

(We can debate whose fault the GPS problems are. But the more relevant thing is that iPhones are more important to Adobe/Lightroom than Lightroom is to Apple. So Lightroom really should adjust.)

Thanks. What surprises me is the inconsistency of it--sometimes Lightroom gets it right, sometimes it doesn't (so sometimes it figures out Apple's non-conforming XMP).  Even when it does, the Map view always has a label in the upper right that says "China" (see pic). I don't know where that comes from--I don't have any metadata presets on import.