Losing Portrait mode on iPhone X

Hi, since I got my iPhone X in March, I've shot a few hundred photos in "Portrait" mode, but last week I noticed that my Portrait album was empty. I went back to some of the photos that I know I've shot in Portrait mode, and confirmed that they are all still there in my phone, however, they are no longer in Portrait mode. I have to "edit" to add Portrait Mode back, and did so for about 20-30 photos to test. They showed up in the Portrait album just fine. However, those photos lost the "portrait" feature again, back to just a regular photo, and once again disappeared from the Portrait album in a couple of days. Why is this happening? My photos are not retaining the Portrait feature for some reason.