Thiourea is a fixing agent that helps accelerate the dye bleach reaction.

Since the "paper" is really plastic, the wash will proceed rapidly in the fully swollen emulsion. But, be careful. There are known cases of browning of Dye Transfer prints due to under fixing and/or under washing.

I do not recommend storing chromogenic and dye bleach prints together. You will notice a strong odor from the dye bleach prints after a few years. IDK what the reason is.