I have had 2 different clients supply PDF files to me that they have edited.
Printing the documents direct to the printer works fine, but as soon as I import the PDF into InDesign the edited text is removed.
The text put in by my client doesn't appear as a layer and I cannot OCR it.
All checks I do are not bringing back any errors. These are multipage PDF files, while saving individual pages as jpegs/tiffs works, this takes up alot of time I do not have.
Please tell the OS you work on.
Also check if Acrobat is updated to the latest patch?
Try to replicate the issue with a sample PDF and compare the outcome.
Clearly not an issue that will be fixed by updating your own Acrobat, since it isn't involved here. I wonder if the clients have used annotations? If so, InDesign won't import these notes, only real text. Discussed here: PDF Comments Disappear Upon Placing into InDesign CS5