Blynk.setProperty on slider

I use 20 sliders to represent the state of machines controlled by the Arduino Mega.

The codes are similar for all 20. The color of the slider must reflect the state of the machine. For the first 3 machines/sliders, no problem. However, from machine 4, the value of the virtual pin is properly transferred but the setProperty to change the color does not work!

//First 3 no problem
BLYNK_WRITE(V0){Mach[0].State = param.asInt();
if(Mach[0].State == 0){Blynk.virtualWrite(V0,0);Blynk.setProperty(V0,"color","#000000");}// not exist = black
if(Mach[0].State == 1){Blynk.virtualWrite(V0,1);Blynk.setProperty(V0,"color","#D3435C");}//red= out of order
}
BLYNK_WRITE(V1){Mach[1].State = param.asInt();
if(Mach[1].State == 0){Blynk.virtualWrite(V1,0);Blynk.setProperty(V1,"color","#000000");}// not exist = black
if(Mach[1].State == 1){Blynk.virtualWrite(V1,1);Blynk.setProperty(V1,"color","#D3435C");}//red= out of order
}
BLYNK_WRITE(V2){Mach[2].State = param.asInt();
if(Mach[2].State == 0){Blynk.virtualWrite(V2,0);Blynk.setProperty(V2,"color","#000000");}// not exist = black
if(Mach[2].State == 1){Blynk.virtualWrite(V2,1);Blynk.setProperty(V2,"color","#D3435C");}//red= out of order
}

//From here, set Property does nothing...
BLYNK_WRITE(V3){Mach[3].State = param.asInt();
if(Mach[3].State == 0){Blynk.virtualWrite(V3,0);Blynk.setProperty(V3,"color","#000000");}// not exist = black
if(Mach[3].State == 1){Blynk.virtualWrite(V3,1);Blynk.setProperty(V3,"color","#D3435C");}//red= out of order
}

BLYNK_WRITE(V4){Mach[4].State = param.asInt();
if(Mach[4].State == 0){Blynk.virtualWrite(V4,0);Blynk.setProperty(V4,"color","#000000");}// not exist = black
if(Mach[4].State == 1){Blynk.virtualWrite(V4,1);Blynk.setProperty(V4,"color","#D3435C");}//red= out of order
}
...

I also notice that the value of the sliders change without any reason. Sliders can have value from 0 to 4. Standard position is 3. While I have no code to set a slider value to 4, I see sliders moving from 3 to 4 when I reopen the app. (And 4 is the position to start a machine :frowning: )

Hello. iOS? Android? What version? Cloud/Local? What range on widget with V3?

Android 5.1
All sliders (V0 to V20) have values from 0 to4