SD card photos

I'm trying to copy photos from an SD card to my Photos app on my Ipad Pro. I can see the photos in the Files App and, if I open just one of the photo files, it will let me save that one individual photo to Photos. However, the Import tab of the Photos app is not opening, either automatically or manually, to let me import all the photos on the SD card. Maybe it's because the photos were copied onto the SD card from my pc rather directly from a camera, but if I can save one of those photos why won't the Import tab open to let me save them all?