Q: Apple mail unable to save PDF from gmail accounts

Hi. I have apple mail on El Capitain 10.11.6 on a macbook air.

Recently, and I cannot remember if it was after a particular update or not, I am now unable to print an email as a PDF or save it as a PDF and or open it in preview as a PDF specifically from gmail accounts. Other accounts appear to work. The sequence of events is:

- File > Print

- Box appears saying generating content for about 5 seconds

- Normal screen saying print like this:

- Then when I chose save to PDF or open PDF in preview the following screen appears which cannot be closed (you have to force quite mail) and no PDF is generated:

I can save these emails as RTF but it is a little frustrating as I need to upload them for work to a database which requires PDF.

Thanks in advance you clever people