RE: Customer journey not working
Hi,
This is caused by the existence of a duplicate contact in the contact submission form.

A customer journey can be seen as a one-way pipeline, so a contact can only be processed once by a journey.
It is by design.
You can set the customer journey as a recurring one.
Please refer to the following section to know more about recurring journey.
Set up a recurring journey
But the Recurrence interval needs to be at least one day.
So if in your requirements you have contacts submitting the same form multiple times in one day, then customer journey cannot accommodate sending an email for each submission and therefore you need to find another way.
In addition
Here is the link of the forum for Dynamics 365 Marketing.
Dynamics 365 Marketing - Forums, Blogs, Support