PDFmaker unable to save Excel file before creating PDF, but works in Word

I am trying to create a PDF in MS Excel 365 (using Windows 10), but I get a popup box stating PDFMaker needs to save the file before continuing. 

I have tried to continuing by clicking at different times the yes and no button, but either way, I get the following error.

The AutoSave feature is always turned on for all of my files (both Excel and Word), but I have turned it off as another troubleshooting idea.

I have no problem creating PDF's in MS Word, this only happens in MS Excel. I have uninstalled and reinstalled Adobe Acrobat, and I ran the full MS Office Online repair, re-starting my computer every time I make a change. I know I can disable the add-in for MS Office and create PDF's from the Export function, but I like the ability to create PDF's and send out for signature that comes with the add-in.