Having updated to macOS 13 “Ventura”, using DT 3.8.6 imprinter seems to be affected by a bug.
If I select a PDF + Text and
Tools > Imprinter > myImprint then the PDF seems unaffected - no imprint appears. The document is, however, actually imprinted - the imprint becomes visible after switching away and back to the PDF in question.
I have tried setting up a new imprint, which displays the same behaviour however.