I used to just use acrobat's find feature, to search for a word and a scanned or imaged based PDF would run OCR to recognize the text. Now, I've clicked Edit PDF on the right pane on multiple scanned PDF files and OCR won't run. The box to recognize text is greyed. These PDFs are not locked. I'm not sure why it's so difficult to run OCR on my scanned PDFs. What did acrobat change in pro that made this feature so neutered?