Using incorrect channel prefix for DIAG_L0 node to channel list file
The L1 DIAG_L0 Guardian uses the L0 prefix, so channels are L0:GRD-DIAG_L0_. However, when 'guardctrl enable...' is done for any node, it writes them as L1:GRD-DIAG_L0_ in L1EPICS_GRD.ini. Only work-around currently is to hand-edit that file as the 'guardian' user from l1guardian.
This was present in the Python2 version on Debian 9 as well