Slim Keyboard on Venue 11 Pro - Keyboard stops working

Hi, I am using a Slim Keyboard on my Venue 11 Pro, but I’ve got an issue regarding the keyboard and I was wondering if it’s an expected behavior or the keyboard needs to be replaced.

If I use my Venue with keyboard on a hard and flat surface (e.g. a table), no problems: keyboard and touchpad work fine. However, if I place my Venue on a soft surface (e.g. trying to type something while sitting in bed) the keyboard and touchpad stop working. I noticed that if the part highlighted in the picture bends, even slightly, the keyboard doesn’t work anymore.

Is this an expected behavior or should I ask for a replacement?