The warning "An object recognition hint. See Additional Information for details." is always displayed, when an object is used and not found.
When testing if an object exists, the warning is not needed. Not finding the object in that case is not necessary a problem. Not generating warning when testing the Exists property, would also make "legitimate" object recognition hints easier to find and fix.
At least, it would be convenient, to have an option to turn it off at the project level.