PDF Embed API - Prefilled AcroForm field text becomes clipped/invisible after editing in Viewer SDK

We are using Adobe PDF Embed API to display and edit PDF forms containing AcroForm fields.

Some of the PDF fields are already populated by a third-party clinic before the document is loaded into our application. These prefilled values display correctly when the PDF is initially opened.

However, when a user clicks into one of these prefilled fields and edits the value, the text rendering becomes incorrect. The updated text appears clipped, partially hidden, or misaligned within the field boundaries.

Expected Behavior

When a user edits a prefilled form field, the text should remain fully visible and properly positioned inside the field.

Actual Behavior

After editing certain prefilled fields:

• Text becomes partially hidden or clipped.
• Text appears misaligned within the field area.
• The original prefilled value displays correctly before editing.
• The issue occurs only after the field is modified through Adobe PDF Embed API.

Steps to Reproduce

1. Open the attached PDF using Adobe PDF Embed API.
2. Navigate to the vaccine section of the form.
3. Locate a prefilled field containing values such as "IMMUNE".
4. Click the field and modify the value.
5. Observe that the text is no longer rendered correctly and becomes clipped or partially invisible.

Additional Observations

• The issue appears to affect specific AcroForm text fields.
• The original PDF renders correctly before any edits are made.
• The problem occurs after Adobe Viewer regenerates the field appearance following user input.
• We suspect the issue may be related to AcroForm appearance stream generation, font sizing, default appearance settings (/DA), or embedded font handling.

Environment

• Adobe PDF Embed API / Viewer SDK
• Browser: [Browser Name + Version]
• Operating System: [OS]
• Viewer SDK Version: [Version]

Attachments

• Original PDF
• Screenshots showing:
  • Field rendering before edit
  • Field rendering after edit

Questions

1. Is this a known issue with PDF Embed API form editing?
2. Does the Viewer SDK regenerate AcroForm appearance streams differently from Acrobat Desktop?
3. Are there recommended settings or workarounds for preserving field appearance when editing prefilled form fields?
4. Is there a way to force regeneration of field appearances using embedded fonts or fixed font sizes?