I would like to help but I use Lbs. My FS program accepts .5 (ie 200.5).
I am sure you have tried this but how about trying .5 then trying 1/2. That might work. And I am sure you have your FS program set to metric. And I assume that you enter your new weight at the weigh in page using the new weight, not the weight loss.
These are dumb suggestions, but sometimes they get overlooked. Other than playing around with the various pages, perhaps your next step is to contact the FS coding Gurus at the help page.
AS has been said, Gratz on your loss, and good luck.
The Perfect Speed
"any number is a limit, and perfection doesn't have limits.
Perfect speed, my son, is being there.”
Chiang from "Jonathan Livingston Seagull