Photos not importing metadata

I've always imported all my phone's photos and videos to a Photos Library on my External Hard drive, I just recently noticed that on a lot of my pictures, none of the metadata was imported with my photos, it got replaced with the date it got imported. This is very frustrating as I've deleted pictures/videos on my phone that I thought were in my Photos Library but all the correct metadata info is gone. When I tried to re-import some of pictures with the incorrect metadata (even though Photos says its already been imported,) it still will import the wrong metadata and replace it with today's date. Any advice to why it's not importing the metadata? Or how I can fix this?