Microsoft Excel prints worksheets as individual PDF's if DPI settings are not consistent within the file.
For example if one worksheet is setup with a different DPI print setting to the rest of the workbook, this workbook will then print (using Print Entire Workbook) as two files, one for each set of DPI settings - the Home page in one PDF, the rest of the workpaper in a separate PDF.
If this issue is encountered the following workaround can be applied.
In the workbook, select the worksheet you wish to update, go to >Page Layout >Expand Button >choose the DPI setting you wish to set for consistency across the workbook.
Alternatively you can change all sheets at once, by >Right-clicking on any worksheet tab, >>Page Layout >Expand Button >choose the DPI setting you wish to set for consistency across the workbook.
***Note: this will change all the Print Settings for each page.
To overcome this issue, updated Smart Workpaper Starter Files for 'Accounts and Tax 2017 and 2018' with updated printer settings have been uploaded on the website, with Starter Files being updated by the end of May 2018.