Rain of Arrows Rogue is Bugged... Please help

Since season 8 dropped my Rain of Arrows Rogue no longer functions… I have 155 energy and am using beastfall boots so everytime I cast a core skill I should take 10 seconds off my RoA cooldown time which is currently at 9 seconds… making it so I should be able to cast a core skill and then instantly my RoA. It works 50% of the time but the other 50% it only lowers my cooldown by 5 seconds. This is essential to my build and I’ve spent hours trying to figure out why. It has to be bugged in some way. Please help as I can’t play season 8 without completely changing my whole build.