[Kibana] [Bar chart]There's no 'Split Slice' option any more

Hi Team,
I am creating a bar chart with trying to adding multi sub-buckets. But when I tried to add second sub-buckets, there's only 'Split Chart' option for me to select, and there's no 'Split Slice' option.
Please refer to my screeshot below. What's the issue here??

Hmm, what version of Kibana are you using? Are you referring to "Split series?" In my installation of 7.3 I'm able to see it even after selecting a single series split.

Hi Lucas,

I am using "kibana-7.0.1-windows-x86_64".

Thanks,
Cherie