Welcome to TVPaint Community forums !

I'm on Windows 10, using 2 displays. When I enable undockable panels, I am consistently getting an issue where undocked panels will always appear underneath the focused TVP window! On top of that, If I open for example the FX panel, it is always appearing on my main monitor but I'll never know because it always opens underneath all of my current windows...

To be quite honest, all I want to be able to do is simply undock my timeline without having to mess with these new window features of tvp.

What kind of startup configuration setting are you using? I had this issue when first starting v12 and I believe due to bringing over my old config which used multiple screens. The panels would open underneath other panels or in unexpected places and be hidden the first time I opened them, but only that first time. I use "Remember last used configuration" and once I put them in the correct place it didn't seem to happen again, so I wasn't sure if it was a bug or a feature with the new system. I am not sure if this is related to your issue but thought I would mention it.