This came up with the PDF in PDFBOX-4627... the pattern was invisible. This is because interpolation is currently disabled for all stencils. This invisibility problem is solved by using the rendering hints when a stencil is downscaled. Currently we don't, due to a past problem with the file survey.pdf (
PDFBOX-1094). However this problem no longer occurs, likely due to other changes in the last 5 years.