I Slavq,
This isn’t a bug, this is how the Construction Script is supposed to work. The value is generated when the asset is created and stays that number, You can easily see this is you set a vector variable that is set from the Make Vector node then just setup it to print on event tick or keypress from the Event Graph to show the value.
If you want to setup any sort of random streams values in a Construction Script you can check out this video here for a demonstration: - YouTube
Thank you!
Tim