"That OCR problem" clearly means more to you than it did to me, but I gather this is to do with the OCR Image action that uses the Tessaract OCR engine. I should try it some time! 
A search of the forum yields a discussion that contains the following information from @peternlewis:
this is an error Tesseract reports (more or less all the time), and Keyboard Maestro hides the error from you normally. However, if nothing is returned as matched text, then Keyboard Maestro returns the error response, which includes this message.
I see that this is indeed a common error message from Tessaract, not restricted to its use in Keyboard Maestro.