I did have the same issue after the 4.01 patch. Normally my mouse cycles through the lights, but after the patch, my mouse is just fully dark. It looks like it wouldn't be plugged in. Then it either doesn't click in the game itself, or would double click even tho it's just clicked once. It works under regular windows and any other application, but the moment the ffxiv border less window is active it doesn't. I tried restarting pc, re installing the drivers, plug it in and out, hell I even completely opened it and took a look at the inside, thinking there might be a problem with the buttons/springs etc itself. I even set the launcher config to default, and the mouse config to default etc. Nothing helps, the only way I got it to work, log in the game, after you're logged in, alt tab, open the software that's responsible for your mouse if you're having a gaming mouse, then click save even tho you haven't changed anything and exit. While my mouse still doesn't show or cycles through the lights as usual when on the game itself, at least it responses again. Not sure what's causing it but as long as it works that way then I am happy lol. Give it a try?