Some things to check:
1. Check the permissions of the TFTP Server. We use the SNMP/TFTP option but had a lot of issues with permissions.
2. Make sure there are no firewalls blocking TFTP. TFTP uses high port numbers for communication and these are usually stopped by firewalls.
3. Make sure there are no ACL's on the devices themselves stopping either SSH or TFTP.
4. Use a sniffer (tcpdump/wireshark) to see what is going on - it helps.
basically when you click the update config button, Spectrum writes the SCM_ file to the TFTP directory, then uses TFTP to send it - after it's done or has an error the SCM_ file is removed again.
Regards,
Frank