CB 8.5 Chord track: sus4/7/b9 chord sounds as sus4/7/9

In my chord track listening to the chord that has been entered as Gsus4/7/b9 chord. It sounds always as Gsus4/7/9 (ignoring the flat on the 9, so i’m hearing an additional “a” instead of the wanted a-flat) clashing horribly with the rest of the arrangement.

Via the UI, it is not possible to enter this chord because the b9 is disabled as soon you select sus4. -> why? I can make the right graphical chord presentation appear when I play it on the midi keyboard but when it is played back it ignores the flat on the 9.

Note: I’ve found out that I can make this chord sound using “D half diminished 7 with a G in the bass”, but that’s somewhat counter intuitive