Please reboot node once and try again. Why are you doing upgrade from sg-reconfigure command? if reboot does not solve it take tcpdumps on the smc facing interface and open a ticket to support
Also please make sure that SMC hasn't been installed using 256-bit security option. You can check this in Configuration --> Administration --> Other Elements --> Internal Certificate Authorities. If Internal CA type is ECDSA, then SMC has been installed using 256-bit security and this option also needs to be selected on engine side when doing initial contact.
Thanks for the answer and I will update the answer to customer.