LLM filter in a buyer-intent tool was blamed for empty outputs; the cause was a billing guard

A team behind Leadolovets, a service that scans open Telegram chats for buying intent, found that keyword search returned 542,795 matches but only 14,774 were real requests. Their LLM filter appeared to fail under parallel load, returning empty responses in 118 of 225 calls. The real cause was a billing check that returns an empty result instantly for accounts with expired subscriptions, so the model was never called. After fixing the test harness, the model answered all parallel and batched tests without failure. Measured on 100 requests from paying customers, the filter removed 95% of junk while losing about 18% of good requests, a figure the team later estimated closer to 5% after reviewing labeling errors.