422 Unprocessable Content Error when adding bundle product to cart

[anthony-v-sundae-lane]

I'm getting intermittent 422 Unprocessable Content errors on Merchants stores when adding bundle products to cart that run Expand.

There's no reliable way to replicate the error despite some lengthy investigation, and the payloads for successful and non successful add to cart calls are exactly the same.

The bundle does successfully add to cart which and shows a success in Functions logs, but the user (and the merchant) is presented with a storefront error - which is a huge issue for public apps.

Example payload that caused 422
form_type: product utf8: ✓ id: 44061997924507 product-id: 7853945389211 section-id: template--16459352408219__main properties[_bundleId]: KPVA-44061997924507 properties[_selectedItems]: [{"i":"44061751312539","q":1,"s":1},{"i":"44061795254427","q":1,"s":1},{"i":"44061783949467","q":1,"s":1}] quantity: 1 sections: cart-notification-product,cart-notification-button,cart-icon-bubble sections_url: /products/product-handle

Response:
{ "status": 422, "message": "Cart Error", "description": "All 0 {product name} are in your cart." }

Is this a bug?