iOS devices such as iPhone (7 and above), iPad Pro (10.5-inch), and iPad Pro 12.9 (2nd generation) captures photos and videos using HEIC/HEVC (“High Efficiency”) codec by default. If you use the Keep Originals option to transfer the media files, then Elements 2019 might not be able to import the media files. This issue is notices on Windows platform and on Mac with OS 10.12 or below.
This issue is not experienced on devices using Mac OS 10.13 or later.
With these settings, when you transfer HEIF images from an iOS device to your Windows or Mac machine, they are converted into JPEG format. Similarly, HEVC format video files are automatically converted into AVC format.
To learn how to transfer images from iOS devices, see Transfer photos and videos from your iPhone, iPad, or iPod touch article in Apple Support site.