Exported PDFs are missing some elements or not opening at all in Acrobat Reader.
I thought at first it was an Acrobat issue with dotted lines as here but I have changed them to unbroken lines and it’s still happening. It’s also happening in Xodo Reader so not an Acrobat problem.
I used the workaround in the thread linked above - launch the Preview app, open the PDF from within the Preview app, ‘Export as PDF’ (not ‘Export’>PDF), then open from Reader.
I can send a file if useful.