Incorrect contact status

Software version: Latest from Android App store - Mayola

I have tested this on 5 Android devices with 5 different accounts, all of them on different networks with just IPv4 NAT - no firewalls on the router blocking any ports. All the devices have DHT enabled, UPnP enabled, TURN enabled, Local peer discovery enabled. All of them have a "username".

All the 5 devices have each other in their contact list.

I brought all the contacts online.

Then I chose one device and manually turned it to offline - by flicking the toggle switch in the Accounts tab.

Then I disabled WiFi on that same device. Mobile data was also disabled.

Now even after 2 hours - this device which is Offline is appearing as online for the other clients.

I notice there is a field called Registration Expire in the Advanced section of accounts - what is it supposed to do? it is currently defaulting to 60 - is it seconds or minutes or hours?