Input on-time process

I’m trying to use “input on-time” process to log presence - seconds I am present at home.
I get updates of presence (1 for present, 0 for absent) at irregular intervals (at state change, so I am using PHPTIMESERIES storage engine) and the “input on-time” process is calculating some strange results.
It looks like it is increasing itself when the input state is 0 and it does not increase when the input is 1.

Shouldn’t it be the other way around - log seconds when input is above 0?
Or maybe, I should be getting input updates at a regular interval for the process to work correctly?