buildNvidiaTaskSet only treated ParallelGPUs as a reason to keep all selected GPUs in one task, so ramp-up (StaggerGPUStart) fell through to per-model task splitting. When that split left a single GPU in a task, resolveNvidiaRampPlan silently returned StaggerSeconds=0, making the ramp-up toggle a no-op. Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>