Knowledge Retrieval returns empty results or hangs in Retrieval Test even when document status is AVAILABLE

Discussion
1

Hi, I am testing Dify Cloud on the free plan and am seeing a persistent issue with Knowledge Retrieval.

Summary

I created a knowledge base, uploaded a single document, and confirmed that the document status became AVAILABLE. However:

  • In Retrieval Test, entering a very simple query such as retention does not return any result.

  • In some cases, the Retrieval Test stays in a testing state for several minutes without completing.

  • In workflow execution, the Knowledge Retrieval node returns an empty result, even though the downstream LLM node still produces an answer.

What I tested

I tried the following multiple times:

  1. Created a new knowledge base from scratch

  2. Tested with both:

    • a .md file

    • a .pdf file

  3. Confirmed document status is AVAILABLE

  4. Set retrieval mode to Hybrid

  5. Set knowledge-base-level retrieval settings to:

    • Top-K = 5

    • Threshold = Off

  6. Left node-level retrieval settings at default:

    • Top-K = 4

    • Threshold = Off

  7. Confirmed that the workflow input variable (for example, business_problem) is passed correctly

  8. Added the retrieved Context variable properly in the LLM prompt

Current behavior

  • business_problem is correctly populated

  • Knowledge Retrieval node still returns an empty result

  • Retrieval Test also returns nothing, or hangs for a long time

  • Usage information from the retrieval node is all zero:

{
  "usage": {
    "prompt_tokens": 0,
    "prompt_unit_price": "0.0",
    "prompt_price_unit": "0.0",
    "prompt_price": "0.0",
    "completion_tokens": 0,
    "completion_unit_price": "0.0",
    "completion_price_unit": "0.0",
    "completion_price": "0.0",
    "total_tokens": 0,
    "total_price": "0.0",
    "currency": "USD",
    "latency": 0,
    "time_to_first_token": null,
    "time_to_generate": null
  }
}

Expected behavior

For a simple query like retention, I would expect Retrieval Test to return at least one matched chunk from the uploaded document, and the Knowledge Retrieval node to produce a non-empty result.

Question

Is this likely to be:

  • a Dify Cloud issue,

  • a known retrieval/indexing bug,

  • or am I missing a required setting somewhere?

Any guidance would be appreciated.