Wondering if water is actually leaking at the crack? My 35 year old steps in my Foxxx IG pool have quite a few cracks and look pretty bad but are not leaking. In still water, no pump running, try a little dye right at the crack. For this iny area you can use food dye or even the phenol red pH reagent. Just a couple drops is all you should need. If I get ambitious later I'll post a couple pics.
Al