Multivalue extension field can't be mandatory with rules control

[HaoweiYG]

Hi developers,

I used Multivalue control extension for multiple selections. I also hope to make this multivalue field mandatory if another field is defined to something by creating a rule. But, I found the conditional rule is not working for the multivalue field.

Here are the steps:
I firstly defined a picklist field called “baisc field” and I use the multivalue extension to select it.

The condition is when “isMandatory” equals to True, “baisc field” is a mandatory to fill. You can see that there is a red icon on “baisc field” but “multi value” extension is still optional. The screenshot shows both fields to see the difference easier.

Thanks