OCR is not supported for DLP Endpoint Prevent
Please refer to Detection Types Supported for On Premises OCR Extraction.
It is possible to get OCR detection with DLP integration with CASB Gatelets and the WSS client. This would happen at the network level rather than the application level.
OCR will never be made available to the DLP endpoint agent as it was found to be too resource intensive and had a negative impact to the user experience.