I use the smart rule to OCR a PDF if it doesn’t have a text layer. Unfortunately a locked PDF seems to meet the criteria and the OCR fails but I end up with a blank PDF (it overwrites the PDF).
Is there a condition I can add to the Smart rule not to OCR a locked PDF?
What version of DEVONthink and macOS are you referring to?
I cannot reproduce this behavior, manually via the Data > OCR menu or a smart rule with the OCR > Apply action.
I ran it again to see if I could reproduce the error. It worked fine this time - probably user (my) error. 
Thanks for checking.
