Wavetable Editor Problem

I started using a trial version of Halion 6 and ran into the following problem: when trying to use the Wavetable editor after creating a new wavetable from a sound file I hit the space bar in order to activate the transport and listen to the result but apparently nothing happens. I also tried to use a MIDI keyboard to play, and while HALion recognises it and shows the incoming MIDI notes in the main view, the Wavetable does not respond to it.
I verified that the software uses my audio interface for playback and I can indeed listen to the original sample in the editor using the Play Tool, so it’s just the playing back of the wavetable that is not working.
Your help will be appreciated!