When I scan a document, I get DEVONthink log messages “Unable to OCR document. Please install ABBYY OCR by going to DEVONthink 3 > Install Add-ons and follow the instructions” for each PDF. That would make sense, except that the OCR action for incoming scans is set to “No Action”.
This is in the v3.9 release on OS X 13.3.1 (22E261) (M1).
That option is meant for scans incoming from a known external source, e.g., the ScanSnap Home software.
Scanning internally in DEVONthink is not controlled by that option. Neither are the Data > OCR commands.