Track Lightbox Form On External Platform



I’ve created an Unbounce landing page which uses a lightbox form.
I need to track this form on Autopilot in order for the form submission to trigger a journey & begin automation.
However, the Autopilot tracking code won’t accept forms in an iframe. I’ve tested a number of things including tracking the form confirmations dialog link, the lightbox page itself etc. (Tracking works when not using the lightbox so it’s just to do with being in an iframe)
Is there any way around this that doesn’t involve Zapier or a third party integration between the 2 softwares?

Of course we can just have the form on the landing page itself, but it seems a waste of the lightbox feature because it can’t be tracked on our other software.

Thanks in advance,