it's because the software crashed again. if you can't click the icon in the taskbar and it wont show up but is running, then its cuz this buggy excuse for software has once again hit the wall.
seems 3.20 is pretty bad, wasn't having the troubles with 3.18 (avoid 3.19 at all costs, the worst offender of them all).
to fix it (temporarily) you have to kill icue in Task manager and then restart the corsair service