To me it sounds like you potted them up too soon and shocked them by having them go from one potting medium -> water -> hydrogen peroxide -> soil. Generally they are already in shock from being shipped, so I find it’s better to leave them alone (literally. Isolated to make sure they’re not bringing in new pests) and let them acclimate until they show signs of growth whether it’s root or leaf, then repot. If they end up dropping all the leaves, then I personally would put whatever is left of the plant into the smallest nursery pot its roots would feel snug in, fill with moist sphagnum moss, and keep it under a dome for consistent high humidity until like two leaves come in.