I'm using Ubuntu on a laptop with external monitor. Normally I had the laptop screen turned off and everything was fine, but I started using both screens and now Spine starts invisible - its window drops shadow on the right of the Unity launcher on the main screen, but apart from that, there is no window on any of the screens...
It looks as if the width of the window is 0.

Also the splash/loading screen appears on the very right of the main screen instead of in the middle of the screen (which might be the beginning of the problem, maybe something with reading the screen size?).

PS. My prefs:

{hotkeysDefault:true,texturePacker:{stripWhitespaceX:true,stripWhitespaceY:true,filterMin:Linear,premultiplyAlpha:true,useIndexes:false,filterMag:Linear,rotation:true},windowMaximized:true,windowWidth:1471,hotkeysVersion:4,glowLogo:false,modeTooptip:false,projectPath:"/home/magnes/workspace/libs/Spine4/projects/lostheroes3.spine",menuTooptip:false,ghosting:{},windowX:119,windowY:87,version:3,showBones:false,recentProjects:["/home/magnes/workspace/libs/Spine4/projects/olga/coin_spin.spine","/home/magnes/workspace/libs/Spine4/projects/olga/shine.spine","/home/magnes/workspace/libs/Spine4/projects/olga/flag_with_skins.spine","/home/magnes/workspace/libs/Spine4/projects/lostheroes0.spine","/home/magnes/workspace/libs/Spine4/projects/lostheroes1.spine","/home/magnes/workspace/libs/Spine4/projects/lostheroes2.spine","/home/magnes/workspace/libs/Spine4/projects/lostheroes3.spine"],windowHeight:780,dopesheetButtonTooptip:false}

PS.2. Changing windowMaximized:true to windowMaximized:false allowed me to start Spine2D - but I can't maximise it because it disapears when I maximise it - so it's no longer a pressing issue, I can work just fine, just have to remember not to maximise. 🙂