I am having an issue with text boxes. I created a text box in a PDF and then assigned the document on Google Classroom. I clicked the option to create a copy for each student. Most of the time students were able to input their text into the box, but some students ran into problems where they would click on the box and my initials would appear. At that point they couldn’t enter text. Again, this wouldn’t happen with all the students, just some.
Maybe because you hit the button when you shared it named Flatten Annotations it doesn’t let anything edit that you did maybe add a new text box if it isn’t that