The fact that things work OK with DCS points to a call sign registration issue on the trust servers.
It takes sometimes as long as three days for new call sign registrations to propagate through the DPLUS trust server to the REF reflectors. XRF and DCS reflectors do not use the trust server system. Since you had very recently done the registration for the new call sign it is likely that your new call hadn't yet been pushed in a trust server update to REF001.
Recommend you give it another try now that a few days have passed.
I'm the sysop of Italian Reflector REF080, I ask you to activate the ref080.dstargateway.org in DPlus_Hosts.txt file (remove #). Many amateur radio contact me because they can not connect because of #.