Fix Shopify Cart Update Issue

My Shopify checkout flow has suddenly broken: when customers add or remove items, the cart total refuses to refresh. No theme edits, new apps, or code changes preceded the fault, so I need a developer who can dive straight into Liquid, JavaScript, and any underlying AJAX calls to trace the root cause and restore a smooth update.

What I expect from you
• Pinpoint the exact conflict or script failure that blocks cart refresh.
• Apply a clean, future-proof fix—no band-aids.
• Verify that the cart, mini-cart, and checkout totals all sync instantly across desktop and mobile.
• Provide a brief report of what went wrong and how you resolved it so I can avoid a repeat.

An understanding of Zoho POS is a welcome bonus; if the issue touches inventory sync or POS callbacks, that knowledge could speed things up.

This is a focused troubleshooting job, so once the cart updates flawlessly and test orders complete without error, the project is done. Let me know your estimated turnaround and any similar Shopify bugs you have crushed before.