Lacking the example code that seems to be buried in private email I can only state that in general it works for me, like this:
if { [form is_request edit] } {
db_1row get_times {
select
to_char(start_date, 'YYYY-MM-DD') as start_date,
...
}
element set_value edit start_date [util::date acquire clock [clock scan $start_date]]
}