Setting perch_forms ID via perch_content field

I'm having trouble getting some forms to work when I try to set the IDs via a perch content text field in the admin. This is the part of the content template:

<perch:form id="<perch:content id="form_id" type="text" label="ID number" divider-before="ID config" help="Coming soon!" />" method="post" app="perch_forms" class="apply">

If I just set the ID normally everything works fine. Debug isn't helping because submit brings up a 500 error. Everything appears as it should when viewing source (the ID being set in the admin pulls through correctly as intended).

Thanks for any help!