Instant modal checkout inside fluent community

Hi,

I'm trying to use the Instant Modal Checkout feature on my site, which runs both FluentCart and FluentCommunity.

Setup:

• I added the PHP filter add_filter('fluent_cart/enable_modal_checkout', '__return_true') via a snippet plugin (frontend only)
• I'm using the [fluent_cart_checkout_button variation_id="X" instant_checkout="yes"] shortcode or the direct checkout URL
• Payment gateway (Stripe) is configured and active

Problem: Instead of opening a popup, clicking the button opens a new page with the checkout — the modal content loads as a full page rather than an overlay.

I tested in normal browsing mode on two different browsers (not private mode), same behavior.

FluentCommunity seems to sanitize content inside Spaces and Courses — is it the issue ?

I also tested placing the button in the sidebar link area (outside of Spaces), same result.

Question: Is there a known way to make Instant Modal Checkout work inside a FluentCommunity environment? Or is there a workaround — for example, a way to trigger the modal via a plain URL parameter so it doesn't rely on JS being loaded in a specific context?

Thanks