This bug was also in 2017.6, not sure how long before that it was also around. After I import a sequence that contained images, if I click on the image in the timeline I get the following Internal Error message:
"Unable to find: ID_CHECKBOX_Pictures_ScaleToFit"
Then the image no longer appears as the link to where the image was stored is broken. Which requires you to re-link to every single image manually using the browse button. This is a problem since you may not know what image the particular effect was linked to. Not to mention on some sequences that contain hundreds of images this could be quite time consuming.
This seems like a fairly straight forward bug to reproduce. So I have chosen to not include any files. If however you need me to include some, I will gladly. I get this bug when importing sequences from old xlights or from super star. Probably will occur with any sequence that contains images.
If I was to take a guess, I would bet that this error has something to do with the fact that image scaling is now handled by a drop down instead of a check box.