{xxxxx_updating_user_email} no longer working

Since a few days/weeks, the notifications we get from our website are incomplete, because the following merge tags do no longer create any output:

• {mitglied_updating_user_email}
• {mitglied_updating_user_login}

Please note that “mitglied” is a custom post type created with the Toolset plugin.

We are running WordPress?6.6.2 and Notification 9.0.1.

Is this a known issue?