It seems that the supplier alerts in 2023 R1 aren't automatically displayed in Generate Purchase Orders - there is just an Alerts column in the Shortfall Details screen which has to be clicked to show the alert(s). See screenshot.
So if the alert is added after an item is confirmed but before orders are generated, it may not be seen. Would it be better to display any supplier alerts when Generate Orders is selected, just before the orders are generated - with OK/Cancel options?