I was unable to reproduce this behavior. Using the attached database, with 'Perform phrase match by default' checked, there are 3 results when searching on
Art. 10
(matching only items that have "Art. 10" in the item text) and 5 results with that option unchecked (also matching items that have Art. and 10 somewhere in the item text).
Please send the info from
https://www.kinook.com/Forum/showthread.php?t=3038