wifi hotspot client list does not list all wifi clients
I figured out my problem. I am using an ethernet-wifi bridge module, which means the wifi client mac does not match the dhcp client hwaddress. This is why it does not show up in the client list. 

I have a static IP address assigned to the bridge, and when I use the wifi mac in my dhcp requests (and set the broadcast flag), then the IP address assigned to my embedded board shows up in the android client list.