Excel retaining .xlsx file extension when exporting to PDF

Hello all,

Im sure this is a very simple thing that I am missing, but out of nowhere it seems Excel has decided to include the file extension in the PDF name when exporting. It never used to do this. Can someone tell me what I am missing here and how to stop this from happening? Just for example say I have a file name ABCSheet.xlsx, when exporting to PDF it is renaming to ABCSheet.xlsx.pdf. Thank you in advance.