Hi
D6 isn't capable of PWM on the ATTiny84 according to the pinout diagram I'm reading here. analogWrite(non-PWM-pin, 255) will result in a HIGH output, which is what you're seeing.
The issue I was mentioning about the enable pin being set to 255 is you do it inside two loops, repeatedly, but there's no need. It will stay at 255 until you change it and elsewhere in the code it is never set to anything else. For that reason I suggested moving it to the init() function where it will be run once and stay that way forever (regardless your choice of a value of i).
Hope that makes more sense.
Cheers ! Geoff