Just to make sure, you do know that the output of the h command (and other commands with outputs) goes to the kernel log and not your current terminal, right? You need to run dmesg to see it.

r~~‭ I suspect that's really the basis of the answer - the key does work, and the question should be clarified along the lines of "why don't I see output...?". Although that depends on what sysrqs are working for OP with more observable effects. Before checking whether the expanded permissions work, OP should verify that ordinary sysrq access is available (e.g. the REISUB sequence).