Using |t or |t('freeform) in html element causes a Twig Syntax Error

[samuel-clara]

What happened?

When adding {{ "CONF_S1_OP"|t }} or {{ "CONF_S1_OP"|t('freeform') }} to an HTML element and activate the "Allow twig" option a Twig Syntax Error occurs.

Errors and Stack Trace (if available)

Unknown "t" filter. Did you mean "date", "trim", "sort", "last", "title", "split", "batch", "first", "format", "filter", "length", "default", "striptags", "capitalize", "date_modify", "number_format", "convert_encoding" in "__string_template__6fc08b0ee80e4e0d03b0488a99918024" at line 1?

How can we reproduce this?

1. Add an HTML element to a form with |t filter
2. render the form on a template
3. Twig Syntax Error

Environment

• Freeform Pro 5.5.5
• Craft 5.2.9

[samuel-clara]

Disabling "Render HTML block Twig in Isolated Mode" under Settings → Form Builder solves this.