im having exact same errors but with pure rx580 rig(no vegas), rx470/480rig, and rx570 rig, and on all of them im getting error that my gpu1(display output gpu) is dead.
tried with adding line set GPU_MAX_WORKGROUP_SIZE=256 but no luck, tried lovering clocks, no luck.
for the algo maybe u can add CN revere waltz algo for GRAFT coin