Hello,
I saw the screenshot you attached and also visits your site. You are using the social buttons type as “Follow” for desktop header that’s why the “Instagram” shown in desktop and you are using the “Buttons type” as “Share” inside the mobile layout that’s why Instagram not shown . Instagram is not available for sharing because Instagram does not share anything by its nature, that is why you cannot add share button for Instagram.
So to fix this Go to WoodMart >> Header Builder >>Your default Header >> Switch to mobile layout and edit the social buttons and select the “Follow” button type and then check the results after clearing your site and browser cache. This will surely fix the issue.
Screenshot for clarification: https://ibb.co/j4K7HWR
Best Regards.