"Invisible" text in filled form

[Jan Schaumlöffel <ja...@vivai.de>]

Hello,

I am using PDFBox for the following workflow:

1) create a new PDF document as a destination
2) read a PDF document template that contains a form
3) fill the form in the template (PDTextbox and PDCheckbox)
4) append the filled template to the destination document using a
PDFMergerUtility instance
5) write the destination document to a stream

(Steps 2 through 4 are repeated as necessary.)

This actually works pretty well for me, that is, as long as I view the
resulting document in OSX's "Preview" PDF viewer.
When I open the PDF in Adobe Acrobat (version tested is 9.4), text
filled into forms is invisible until the field is clicked. When another
field is clicked, the content disappears again.

When I edit the form in Acrobat and change anything about a form field
(add some text content or save the form field's properties to the same
values as before) this single field starts to work normally.

Has anyone encountered something like this before?
Am I missing a necessary processing step while filling the form fields?

Kind regards,
Jan