Toggle group layer in a layer theme using custom module.

I have several group layers in a layer theme. Some of them are turned off by default.

 

I am trying to toggle a group layer in a layer theme using custom module. But it is not working. By default the group layer visibility is turned off.

 

It does work only if the group layer is turned on in the layer theme by default.

 

 

I am currently using viewer 4.12.

 

 

Is this a bug?

 

 

Regards,

 

Mahender