Symptom
Four fallback stages stacked; ~100 items recorded as "no source." They were in fact recoverable.
Cause
Stage 1 (web search) fails → done[id]="nourl"; continue. Stages 2, 3, and 4 never executed.
The point
The failure reason in a progress file tells you which stage exited, not "every option was exhausted." Before you prescribe based on a failure code, check where in the chain that code gets written.