Hope you are doing well and sorry for the trouble. As described printing the form to Adobe PDF creates the PDF with black checkboxes.
We need some more information for a better understanding.
- What is the version of the Adobe Acrobat DC you are using? To check the version go to Help > About Acrobat and make sure you have the latest version 21.01.20142 installed. Go to Help > Check for Updates
- What is the application you are using for the original source file?
- Is this a behavior with a particular file or with all the files you want to convert to PDF? Please try with a different file and check. If the file is located on a shared network/drive please download i to your computer first and then try again and check.
- What are the steps you are doing to print the document to Adobe PDF? Please try to create the PDF from file menu of Adobe Acrobat DC. Open Acrobat pro DC > File > Create > PDF from File and see if that works for you.
Also please share the screenshot of the issue (Black Checkboxes), the original source file and the created PDF, so that we can check it at our end.