back up keeps coming back to previous day data saved

Hello all,

I just installed ATI 2016 and tried to do my first backup. Obviously, it takes some time (23 Go announced), and time remaining is between 15 hours and 2 days (depending on days). 

Anyway, I knew it so, ok, I let ATI does its job and keep an eye on it. First day, it uploaded circ. 2 Go. Ok. 

2nd day, it uploaded another 1 Go for a total of 3 Go. Ok.

3rd day, when I turned on my computer, I could see that I was back to 2.2 Go saved... Kept running up to 3 Go. 1 day lost?

4th day, same thing: started back at 2.2 Go. No matter how far it goes, it keeps starting back at 2.2. Go saved.

Can anyone tell me what is happening (or should I just give up, delete ATI from my computer, and forget this crazy idee of keeping my data safe) ?

Thanks...