I don't have any idea what causes ricing. I've read it could be because of too high of a temp or FOs added in after the lye causes the oils around it to heat rapidly and saponify ahead of the rest of the oils. Generally, ricing is blamed on fragrance oils. Did you scent it? I've never had any ricing in wine batches but I've had FOs which caused ricing in other batches. Another possibility is there was too much alcohol in the wine. I also don't use 50/50 lye solution because I don't make enough batches for it to be worthwhile to make it ahead. You might have to be a little patient before someone who uses 50/50 lye solution sees your post and is able to give you an answer.
I hope you can save the batch.