beaming with cadenzaOn

[Sam Frybyte]

If there is a time signature the beaming of 8th notes with
acciaccaturas between them is created as I expect.
in version. 2.18.2
with \cadenzaOn
\stemUp\acciaccatura c'8 \stemNeutral a8
    \stemUp\acciaccatura b8 \stemNeutral ges8
    \times 2/3 {f16 [des des]} des4

I have not been able to figure out or find a way for the 8ths to be beamed.
Please direct me to the place in manual where this is found.
Thank you. Or if it's not in the manual and there's a solution that you know
I look forward to knowing this.
Jay