Hi Joey,
Customer journey will only process submission of each contact once, it is by design.
Further explanation: Form submissions are not connected to any particular customer journey, if we have more CJ (active) in the system the form submission will be routed to all of them.
In a word, it is not supported to build such a customer journey that is able to send marketing email for every submission, some users in marketing forum have also reported the behavior and are seeking for a solution.
From your intended alert notification email, it seems that the layout of email is not complex, there are only title and submitted information in the email,
therefore, I suggest you refer to my answer in the thread I posted, use javascript to capture all data of fields when contact submits form, then send these data to http request trigger and send email with flow, it would be the only workaround at present.
Or enabling form level DOI to your form.
Regards,
Clofly