So, if I go to the device of the keypad and select Arm Night, it will Arm Home. No matter what I do.
If i go into HSM and click the box to setup partial button arming to night, save it then go to the device. I can only arm in night mode even if i hit arm home, it goes directly to night no matter what.
I found this post. It doesn't address your issue directly, but has screenshots that might help you with your issue. Because you didn't include screenshots, I'm not sure of your initial settings. But make sure that you're not choosing to "use all". go in and actually choose your devices, or you will have a bigger problem. Hope this helps.
In simply saying that you should check your settings to make sure you're enabling it correctly in hsm. Or post screenshots of your hsm page. It has everything to do with the app.