Actually it isn’t a bug but a behaviour designed to recognise image sequences and deal with them as a single file. Otherwise image sequences like the ones shot cDNG would be an absolute nightmare. That’s why you need to select show stills as individual frames before importing. How else should Resolve deal with this conundrum?
Yes it’s a tad annoying but I just ask anyone making graphics or producing stills to avoid using a number at the end of the file name. It happens from time to time and when I see that behaviour, I delete the files in the bin that are not actually image sequences, tick show as individual and reimport just those bits. It’s not actually renaming anything at the file level, just displaying the range of the image sequence.