The thing is, the amasty_order_attribute_grid indexer on your instance is most likely set to Updated by Schedule mode. To enable the correct display of the order attributes values, the reindex should be run to update the values using the command:
- php bin/magento indexer:reindex amasty_order_attribute_grid
If you don't want to run reindex every time the order is placed, please go to System > Index Management > Order Attributes Grid by Amasty and set it to the Update on Save mode. Now, the values would be updated right away.