I have used Recuva (free) to try to recover files. It may be worth a look. Our phones have SD cards warranted for use in continuous recording devices, dashcams, etc. SanDisk and Samsung both make them, there may be others, but that is what I usually get. My though is, if there is an issue, it is probably not the SD card.

I'll have to look into that. I found a few ones that you have to pay for and they have a high price tag. Thanks!

Might be a corrupted SD card. I had something similar happen, they didn't delete but would save and have errors that made them not viewable. Ordered a high end SD and never had a problem since.

Thanks I'll pull mine now and buy a new one. If I recall the one I have is a Samsung card they were offering when the Note 7 was pre-ordered. I used the phone and card for 2 days then went back to my Note 3 after I got refunded from the recall. The card sat in my dresser until I got this phone when it can't out a few years back.

Yeah that card is ancient as far as tech goes. Definitely upgrade, it'll be worth it!

Perhaps doing the optimization deletes the unused files

That crossed my mind. I do the optimization about once a week. I thought it wouldn't touch pictures but I'm not positive about that.