Unable to capture signature in Docx Template

We're trying to embed signature images into a bulk release receipt PDF using Appian's DOCX template generation.

Problem: We're generating a bulk release receipt PDF in Appian using:

• DOCX Template with bookmarks named signature and signature2
• XML Data Model for text content (case numbers, items, etc.)
• Images Input to embed signature PNG files

snapshot of process model

Template has bookmarks named signature and signature2

What we verified works:

• Signature documents exist (IDs: 432896, 437642)
• todocument(432896) successfully converts IDs to document objects
• Signature files are valid PNGs

We have a separate images input for dynamic docx that is used specifically for embedding the images that returns a map with names and document objects, which maps to bookmarks in Docx Template.
a!localVariables(
  local!firstRelease: index(pv!release, 1, null),
  local!relinquisherSigId: index(
    local!firstRelease,
    "relinquisherSignatureId",
    null
  ),
  local!receiverSigId: index(
    local!firstRelease,
    "recieverSignatureId",
    null
  ),
  a!map(
    signature: if(
      a!isNotNullOrEmpty(local!relinquisherSigId),
      todocument(local!relinquisherSigId),
      null
    ),
    signature2: if(
      a!isNotNullOrEmpty(local!receiverSigId),
      todocument(local!receiverSigId),
      null
    )
  )
).

What's failing:

• Using «${signature}» in template → FreeMarker error: "signature has evaluated to null or missing"
• Using just bookmark names → Shows as hyperlinks, not images
• Using conditionals [#if signature??] → Shows "[No Signature Provided]"

Expected: Signature images embedded at bookmarks in final PDF Actual: FreeMarker errors or blank spaces

Questions:

1. How do you properly map document objects from Images input to DOCX bookmarks?
2. What's the correct syntax for embedding images in XDocReport templates?
3. Are there known issues with signature field documents not embedding?