start_time is "HH:MM:SS" (time only), not a full ISO datetime. Combining with resource's start_date to get "YYYY-MM-DDTHH:MM:SS" before parsing. The ValueError was silently caught on every slot → 0 venues found → recheck never actually ran since it was first deployed. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>