Thanks for your fast replies!
I’m just a beginner with all this, sorry I’m probably not much help.
I’ve updated to the latest WPBakery which didn’t help.
The theme I’m using had both WPBakery and CMB2 come with it.
I’ve worked out how to get around it (probably an obvious thing), I just place another shortcode in where I wanted it through WPBakery, disabled WPBakery and then replaced the shortcode with WPGiftRegistry’s shortcode, and seems to still work when I’ve re-enabled WPBakery.
Seems to be working great – a must have app for any wedding website!