theme does not support ugb/header

I’m new to Stackable and have been testing with a Blocksy theme called ‘Charity’ for now. This theme supposedly is meant to be used with Gutenberg, so I was hoping it would work with Stackable.

At the top of this theme is a header (optionally 2 or 3 rows) that contains the social media icons and other menu items and the title. When I tried editing the page with Stackable I don’t see the header section at all. At one point I did see an error or message that the site/them doesn’t support “ugb/header” whatever that means..but I presume it’s a property used in this header but that Stackable can’t work with.

Anyone know if there is an update or fix that would let Stackable work with this “ugb/header” property?

Thanks..