Cart properties in Shopify POS UI Extension are one state behind (stale data)

Cart properties accessed within a Shopify POS UI Extension appear to be out of sync and consistently lag by one update.

When a cart property is added or updated, the extension does not immediately receive the latest value. Instead, it reflects the previous cart state. This was reproduced by:

  • Adding/updating a cart property

  • Displaying the same cart property via a separate POS UI extension

In all cases, the displayed value was one state behind the most recent update.