In order to obtain the most recent inventory data in the Inventory Planner, it its necessary to manually launch an update by pressing the Update button.
The update operation launched by the Update button must finish within the designated time limit, but some stores can have such an extensive product catalog that the update operation exceeds the time limit and results in an error message. In such case, use a command for a command line interface bin/magento mirasvit:inventory-planner:reindex.