Workflow Emails not sent

[karimj]

I have a Workflow (e.g. send an Email 1 day after the event), but the email is never sent.
When I look in the DB in the table WorflowReminder I see an entry, with scheduled = FALSE.

(I am using the cal.com via docker, currently v.3.9.1-sh)

Is there a setting missing? Is that a bug? Any help would be greatly appreciated.

[karimj]

Update:
I upgraded to the newest version now (4.4.5)
Now the emails show up in the DB with scheduled = TRUE and also have a referenceID, but nothing is sent out.
(all other emails work as expected)