Hi Mike.
Are you sure the break opcode is working in 2.19.9.1? Its not working for me, it shows as NOP, but the exact code works in 2.19.8.1.
Heres the sjasmplus memory output showing as DD01.
21 FDE8 DD 01 break
22 FDEA 21 FC FD ld hl, STRING
23 FDED DD 01 break
Cheers, Dicky