locks/chills/dubious securities. Many firms don't want otc stock deposits. Almost none take paper certs anymore, DWAC or nothing at all. They are tired of the liabilities that come with them. Holds, freezes, lawsuits, unregistered securities, fraudulent opinion letter. When the clearing firm is not perfect in vetting the stock, fines, nothing like fines from FINRA, legal fees, etc.
All so they can collect a couple hundred dollars from a stinky pinky.