Missing or garbled text when combining PDF documents in Acrobat Pro DC?

Are you able to share some information on the settings you are using when converting the initial AutoCAD file to PDF?

• e.g. Are you using the Adobe PDF toolbar in AutoCAD to create the PDF - if yes, what PDF settings are you using?
• or are you using AutoCAD's build-in PDF creator? - You can set font handling properties for DWF files, to Capture None, Capture Some, or Capture All. Use the last setting to ensure all fonts are captured or converted to outlines (not all fonts might be able to be embedded, so some will be converted to outlines in that case).

I'm not an AutoCAD user, but that's a bit of information I came across that might help.

If that's of no help, please try and provide some more information:

• AutoCad Version and specifically how you originally create the initial PDF file that is a part of the combined PDF files.
• Screenshots are always helpful.