For some articles, it showed "No summary available at this moment, please try again later." Does it mean the engine is momentarily overloaded, or the summaries

For some articles, it showed "No summary available at this moment, please try again later." Does it mean the engine is momentarily overloaded, or the summaries are not instant? Perhaps Kagi runs the AI summary service in the background, fed through a human pipeline, then published it? Otherwise, it's hard to explain the curation found by other users and now the non-availability.