Fix Mobile Shopify Inbox Bug

My Shopify store’s Inbox chat icon is fully functional on desktop, yet on any mobile device it looks clickable but never opens. Shopify Support hinted at a clash with either a third-party app or the heavy custom code inside my theme... (Budget: $30 - $80 USD, Jobs: CSS, Debugging, Google Chrome, HTML, JavaScript, Mobile Development, Shopify, Web Development)