Just managed to fix this playing around with where the displays are. I originally tried stacking them horizontally which didn't work. Instead, stack them vertically. In my case, the window was hidden above my left monitor. I moved this monitor so it is below my right monitor which made the window visible. Hope this helps.
Would like to add that I too am having this issue and none of the fixes work permanently between pc boots. I have noticed that there is no window Title right menu. Right click on the top bar of Curseforge client, nothing happens, right click on Discord window title for example and a menu appears with Restore, move, size, Minimize, Maximize. These options are important when the window open offscreen as you can use the keyboard to access this menu. One work around is to right click on task bar cascade windows, the other is to change to portrait mode on the monitor and click on revert in display settings