Hi Kirk! Build 19711.
Original images were from Canon, e.g. BOY_1286.JPG.
When renaming to a longer string, in my case like BOYKO_ICELAND2018_{fnum}, every image that had a .XMP file was renamed incorrectly: the numbers lost initial zeroes, e.g. file 0005 became BOYKO_ICELAND2018_5.JPG, file 0046 became BOYKO_ICELAND2018_46.JPG.
Is this a bug or was I using the rename incorrectly?