Countdown timer to a UNIX timestamp from Firebase

I'm trying to create a simple countdown timer that will expire at a set DateTime taken from Firebase document - like on eBay auction. Here are my settings:

The "DateTime to UNIX Secs" links to a document that I call in a DB query in HomePage widget and specifically, to a dateTime field that is set just few hours later. (I'm sure that the DB call at the top of the HomePage works because it correctly displays various fields from that document throughout the page). But instead I keep getting this:

The remaining hours is definitely wrong and the seconds are not moving (both in Test and Run modes)

It should be very simple, but for the past 4 days I can't get the timer to work at all.

Any help?