Well it looks like mine is indeed broken
Got the new cable today and still has the same flickering/blurring. Tried it in 2 different mini-DP ports on my gpu and tried it connected to my wifes pc (270x gpu) and it's exactly the same. It's even doing it after a while when set to 1440p/60Hz now so it's back to fill out another Benq RMA request. Hopefully they'll deal with it as quickly as they did the firmware upgrade.

Got the new cable today and still has the same flickering/blurring. Tried it in 2 different mini-DP ports on my gpu and tried it connected to my wifes pc (270x gpu) and it's exactly the same. It's even doing it after a while when set to 1440p/60Hz now so it's back to fill out another Benq RMA request. Hopefully they'll deal with it as quickly as they did the firmware upgrade.