Very similar to: Can't load gradle project in NetBeans but I think not exactly the same, if only because of the age of that question.
I saw gradle mes
The Gradle support is a new built-in feature for NetBeans 11. A few weeks ago a source patch was released.
You mentioned NetBeans 9, so I guess before you were using a separate plugin.
So either you try to apply the patch (even though the tickets were not looking like the bug you encounter was adressed) or maybe you could give the plugin another chance. Based on the user comments the plugin in version 2.0.2 works with NetBeans 11.