I have had the same issue. Last season bought some print at home for Leeds game – emails issued with pdfs no problem but this year v Citeh and now Soton. Nothing. So contacted ticket office apparently there is an issue with Ticketmaster and a few are having these types of problems. The club printed off and posted tickets out to me and then also they seem to generate the pdfs via email as well.
Don’t know if they have now resolved completely but it does not seem as though they have.