Mustache - Postmark email conditional formatting - html

Question

I am trying to conditionally render a block of HTML, dependent on the presence of a key in the JSON -> custom_invite_text.
My understanding is that the Mustachio conditions control the presence of the HTML blocks below. This is working fine, but we lose access to the dynamic data provided by the JSON. Presume it is a scoping issue, but some guidance would be good?
The following HTML is used to generate an email:
<p>{{body}}</p>
{{#custom_invite_text}}
<table class="custom_invite">
<tr class="custom_invite_rows">
<td class="custom_invite_row1"><div class="roundel"><p class="roundel-text">{{custom_invite_org}}</p></div></td>
<td class="custom_invite_row2"><p class="custom_invite_heading">From {{org_name}}</p></td>
</tr>
</table>
{{/custom_invite_text}}
{{#custom_invite_text}}
<table class="body-action custom_invite_div" align="center" width="100%" cellpadding="0" cellspacing="0">
<tr>
<td class="custom_invite_text" align="left">
{{{custom_invite_text}}}
</td>
</tr>
<tr class="custom_invite_btn">
<td align="center">
<!-- Border based button https://litmus.com/blog/a-guide-to-bulletproof-buttons-in-email-design -->
<table width="100%" border="0" cellspacing="0" cellpadding="0">
<tr>
<td align="center">
<table border="0" cellspacing="0" cellpadding="0">
<tr>
<td>
{{behaviour_url_description}}
</td>
</tr>
</table>
</td>
</tr>
</table>
</td>
</tr>
</table>
{{/custom_invite_text}}
{{^custom_invite_text}}
<table class="body-action" align="center" width="100%" cellpadding="0" cellspacing="0">
<tr class="custom_invite_btn">
<td align="center">
<!-- Border based button https://litmus.com/blog/a-guide-to-bulletproof-buttons-in-email-design -->
<table width="100%" border="0" cellspacing="0" cellpadding="0">
<tr>
<td align="center">
<table border="0" cellspacing="0" cellpadding="0">
<tr>
<td>
{{behaviour_url_description}}
</td>
</tr>
</table>
</td>
</tr>
</table>
</td>
</tr>
</table>
{{/custom_invite_text}}
Thanks.