How are you exporting to PDF? Are you using the built-in File> Export and then choosing PDF.
Or are you using Distiller? There's a setting in Distiller that could be causing this.
I'm exporting as File>Export.
Check the Adobe PDF preset at the top of the Export dialog box.
Choose something like High Quality Print which comes from Adobe and see if that exports correctly.
Okay will try that. Thank you sincerely.