I am able to replicate this problem consistently.
I am currently trialling Photoshop Elements 2018 on a Windows 10 PC.
I have a raw file and its associated JPEG file sitting side by side in Organiser, followed thereafter by a number of other photos that I wish to delete.
I open up the raw file, edit it, save it as the JPEG file (overwriting the existing one).
I then delete the next few photos.
PE2018 randomly changes the time stamp on the raw file (I cannot quite work out the difference - approximately 15 hours or so).
As my catalog(ue) is sorted by date and time order, this causes the raw file to change its location so it becomes the last file for that day. I originally thought I had deleted the raw file, but undoing the delete did not bring it back. It has taken about two hours of trying to repair the catalog, clean up the cache, delete the album and recreate it and other things before I figured out what was happening by stumbling upon a bunch of raw files!
The common attribute of the raw files that I have noticed this occurring on are that I originally adjusted the time stamps to account for a time zone difference. I suspect, but have not confirmed yet, that PE2018 is undoing my adjustment, but only for a raw file that has been edited in the way I described above and only that file which is closest to the files being deleted.
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