Default value in database not populating

AFAIK the "default value" for a column (when we're talking about the SQL table definition) only applies when adding that column to an existing table with existing entries - and perhaps some other aspects of directly adding new rows to the table directly via SQL commands and/or in the PHPMyAdmin interface - but it has no bearing on what happens when you create new rows in a process (nor does Appian have any insight into what the SQL "default" setting is set to).

Long story short: you'll need to manually populate that value when creating rows in Appian, as always.

It's probably of no consolation but this *does* work if you use the modern Write Records smart service i.e. the default value (for the 'MODIFIED_ON' column in my test example) is set to the value of 'current_timestamp(6)'