Problem was they didn't mature. But I have plenty seeds now.I'm a bit late to the party here but I don't think this pod was fully ripe. In doubt, let it ripen to the point it gets very soft to the touch (almost feeling mushy). It's sometimes the only way to tell for sure that the fruits are ready and seeds fully mature (with most mustard for example). With darker BBG hybrids, sometimes you can have a look under the calyx's edges to see if the color is lighter (see pic below). Also, on most ripe pods the peduncle will become darker with a woody kinda look once they are ready.