Straight and portamento glissandi

I have problems in playback of portamento glissandi in Musescore 4 both in MS basic and the free Musesounds.
I need to work with portamento glissandi in a current project. After many days trying to find a solution I received a message that this function does not work as there is no current recording made within these libraries of portamento glissandi.
Then I check Musehub and found that Spitfire Strings do have these articulations recorded and the sounded well in the specification reviews.
So I bought this library. I have got the library now working. Good sounds, great!
However the portamento glissandi playback does not execute. How is this possible? Please help me here!
Thanks
Peter