We are a new user of ActiveCampaign and have set-up a number of forums.
While experimenting with Modal Forms (Floating) we can see Custom Fields are not available at all, restricted only to Name and Email Address.
This is compare to In-line Forms, where Custom Fields can be included without issue.
I can see that as long ago as May 2016 users have requested the ability to include fields such as Phone Number, is made availability.
Programatically, i cannot think of any reason why this was not made available from Day 1.
ActiveCampaign, can myself and the community please have an update on this?