linux – keyboard layout just change once XFCE DE

I am using Xubuntu 20.04

I want to change my keyboard layout shortcut

I select win + space as a shortcut

my layout are English and farsi

now when I get win + space on keyboard
**
if the layout is English is returns to farsi**
**
but if its farsi it will not return to english **
**
I have to change layout manually by clicking ( can’t change in via keyboard keys)**

note that when I select win-Left as keyboard shortcut layout I don’t have this problem

how can I fix this issue?

but the thing is that I want to set a win key as shortcut to open start menu

and I want to set Win+space as shortcut for changing keyboard layout

how can I solve these problems?

I searched a lot on the web but it seems no have a problem like this