Signature Block for some signed documents don't show text with Acrobat Reader on macOS

The reported is using macOS 10.15 and the latest Acrobat Read Version. I've tried to reproduce with the same versions and can't reproduce.

pdf-as should be embedding the fonts in the PDF, so missing fonts shouldn't be the issue in theory.

-> It's likely that problem is caused/triggered by the input file, thus we need the input file so we can try to reproduce the issue.