python - Flask, one flash message not getting displayed

I know flash is set up properly as all other flash
messages are being displayed correctly.

I have
updated one view. It used to call the flask route from a javascript window.location
function but now am using $.post() to send parameters to the route.

The location of the flash call hasn't changed
(I put a print statement just before it and that executes so I know the interpreter gets
to the flash call).

All code in the route's
method executes correctly but the flash message does not show and I am at a loss.
Nothing coming up from Google searches.

Here are
the last 3 lines in the route
method

db.session.commit()
flash('Database
            Updated')
return
            redirect(url_for('index'))