Opening a constituent record and making any change to it, does not update the date last changed field within properties.
We are currently evaluating this issue and will update this article when we have more information.
Steps to Duplicate
1. Click on Records>Constituents 2. Open any constituent record and make note of the date last changed in properties 3. Make any change to the constituent record 4. Save and close the record 5. Re-open the same constituent record 6. Go to File>Properties and note the date last changed field did not update.