[TYPO3-mvc] T3 6.2 ActionController: flashMessage after redirect issue

[g4-lisz at tonarchiv.ch]

Hi there,

there is some issue in a extension we try to migrate from 4.6 to 6.2:

In the controller class there is an editAction, which displays an edit form.
There is also an updateAction, which is called when the form has been
submittet.

After processing form data, the updateAction redirects to editAction again.
Before doing so, it adds a message using
    $this->addFlashMessage('Saved');

This message is not shown anymore. This was working with T3. 4.6.
When I add a message in updateAction(), it gets displayed. It looks to
me like the flashMessage queue is emptied on a redirect.

I did also try this line:
    $this->addFlashMessage('Message saved.', 'Succes',
\TYPO3\CMS\Core\Messaging\AbstractMessage::OK, TRUE);

The fourth parameter says that the message is also stored in the session,

What I am doing wrong? How can I add a flash message in an update action?

Cheers,
Till