Tryndamere Ultimate

Tryndamere's ultimate is not working in certain situations on the new rift and following patches. It will go on a cooldown which will display an incorrect cooldown, something like 99 or 97 seconds when the CD is 100 Seconds. I have pictures of this to prove it. This glitch has existed in the past (for several months) yet it was EXTREMELY rare in the past months. The glitch has now become much more common to where I can expect to see it about 1/10 games. I'm not sure if it's the smite or certain true damages but it has happened to me several times.