I thought something similar happened to me but I'm not sure. I went looking for one video file I had but couldn't find it. I had no recollection of deleting it, and I was pretty sure I didn't. So I used the file search function ES File Explorer to search the file by name and it found it, but the file wouldn't open. I opened the file properties and the location was correct but everything else was N/A. So I thought OK maybe something's wonky, first step reboot phone. I did, no difference. at this point I didn't have time to investigate further on that day. Next day I did the ES search again, this time no file by that name. So i checked my other files to see if anything else was stolen, but everything else seemed fine, it was just that one video. so in my case I had no option but to close the case as accidental deletion... for now...
But in the meantime I googled the issue and found a post on another site that claimed the issue for him was his antivirus app. he removed the antivirus and things stopped disappearing. maybe you guys should look into that.
