When I choose File>Create>Combine Files into a Single PDF, It should combine files into a single PDF, notAdobe Acrobat Pro DC 2018.011.20040
When I choose File>Create>Combine Files into a Single PDF,
It should COMBINE FILES INTO A SINGLE PDF, not create a portfolio, which is what it does.
Adobe Acrobat Pro DC 2018.011.20040
Windows 10 64bit
Please uncheck the “Save as PDF Portfolio” options in Tools > Combine Files > Options dialog and your issue will be resolved.
Let us know if this doesn’t work out for you.