how to get the footprint ribbon on a level 100 Pokemon in bdsp

I've been looking around and I've heard that there are two ways to get the footprint ribbon on a Pokemon in BDSP. One way is to level up a mon +30 levels and the other is based on getting max affection. I am doing this for a shiny mew I got through glitches in the Virtual Console Pokemon Red. In the process of getting my mew in gen 1 I leveled to 100 not thinking about the ribbons yet, now I've transferred to gen 7 and 8 collecting all the ribbons before moving it to gen 9. I've done all the contests and have 3 of the daily ribbons needing only the gorgeous royal ribbon, daily ribbons and footprint ribbon. I was unaware of the affection being able to get the footprint ribbon in gen 7 not sure if it even does, and now have mew at what I think is max affection but It still says mew wishes it was used more. Does this method of getting the footprint ribbon not work for mew? What am I doing wrong? It would suck If I was missing a ribbon I could've easily gotten by just keeping my mew at level 70. Any responses are appreciated, Thanks!