BGP route-target constraint function is not supported by NE20E-S8A (V800R008C10SPC300), it is supported by the version after NE20E-S8A (V800R009C10).
BGP route-target constraint function is supported by below two versions:
NE40E-X3 (V600R008C10SPC300)
NE05-SQ (V300R002C10SPC200)