Unless proven different by breaking news, THAT is a crack resulting from the recurving process. 3/4" is too thick, with any wood I know of. I have done this exact thing two dozen times, and it's an easy fix.
Get a plane, sandpaper, double cut flat file, and/ or scraper, and flatten the belly of the limb for a couple inches each side, flat LATERALLY, even, and long enough to matter. Then cut a 1/8" slat of something beatiful and strong, prebend it to the original curve with boiling, steam, or microwave. Glue it on and blend it with the limb./ Presto, beautiful overlay, and durable recurves.