HoloLens 1: Gestures not recognized in Unity 2019.4 with MRTK 2.8.3

I own an HoloLens 1 and so far I have developed some AR projects with Unity 2018.4.23f1 using the HoloToolkit (the version available in 2018). Now I want to develop a new project for HoloLens 1 with ...