fast io assignment ignored

I used a fast io assignment for my input and output flops

and it got ignored in the fitter (listed as such in the fitter report)

I am guesing this is because of using a global clock to clock the io register?

(I am using fast io register to meet timing along a path and regular flops clock to q

seems high)

Is there a way I can use Fast IO and clock it by a global clock (clock is output of PLL and getting distributed on a global clock line)