Hey c-attack and Baio, problem solved!! I simply reversed F#1 with Fan#2 connector and for some reason they all work again. It must have been a glitch in the software or a bad connection. Anyway, thanks to both of you for your prompt replies. Keep safe and well.
P.S. c-attack, the fans are all connected to the splitter that comes from the pump. This is one of the reasons that I was confused because I thought, as you stated, they should all be doing the same thing. Oh well, the problem is solved for now. Thanks, again!!