I find the correct image on the menu and copy and replace it in the corresponding position on the timeline, and all seems well. I usually do a manual Ssave at that time too. When editing a sequence of several hundred photos, itis a pain to go through again and again and discover that a random number of images have been substituted in this manner.
I am not positive of a pattern but it seems the substituted photos are often ones on which I have used the "Enhance Image" tool. It may be that the enhance tool is adding that singular image that is being substituted as well doing the Enhance (perhaps the first image enhanced follows the tool to further images, but not every enhanced image). I have not yet discovered a pattern.
On the previous project, I was using images from seven different devices. The substituting image was from the ASUS Zenfone3, which used a date/time stamp for ID. Example "20180117_111620" which is the date plus 11:16:20 time stamp. I thought that the time stamp may be overriding the various images other ID code, so after trying various other things, I gave the interfering photo a new name, removed the original from the project and deleted it from my PC. I cannot remember which photos this image had been imposing itself on.
On thiscurrent project, most of my photos were from a Nikon camera with ID coding like "_600xxxx". The specific interfering cropped and enhanced photo was from a Canon G5x, with ID coding "IMG_0666". I did not record if the photos being overlayed were from the Nikon, a Canon Rugby phone or that ASUS Zenfone3, but I think they were all on the Nikon images.
Anyone finding similar anomalies with suggest sequence for easiest correction?