Quick question....
If you can't access the other character panels in the prologue now, but you can and do have full control over them in combat (and it makes very little sense to have those two things side by side)...
So...
What happens, for example, if you drag a spell of Shadow's bar by accident?
How do you put it back?
Plain and simply: you can't.
You are able to do something to your UI that you then cannot undo.
This is an abject failure of design at the most fundamental level - and once again, it's assign of them doing something with zero foresight and no care for extended consequences.
I've got a file right now with Lae'zel and Shadowheart in the nautilod with completely empty skill bars, and the result is that they are seemingly incapable of taking any actions other than basic melee attacks (ranged in Lae'zel's case; shadow doesn't have a ranged weapon).
I cannot fix this. I cannot change this. Interacting with the UI has, to all appearances, broken these characters of their ability to use their skills and spell, in a way that is irreversible and cannot now be fixed.
Now... there IS one way to access their abilities still, but the game does not tell you about this or indicate that it is possible in any way - indeed, it's pretty counter-intuitive and anew player is not going to discover it except by random frustrated clicking; you have buttons down the bottom that sort your hot bar tabs, and these are clearly marked. Your resource bar up the top shows your action, bonus action, and class resources available - these do not look like buttons, are in a different place and have a different visual appearance to the other buttons, and give no indication that they are also clickable things - they look more simply like a resource tracker. These will bring up an unmodifiable bar of the things associated with that resource - it will lay this out as it chooses and you can't change it, and you can access your abilities through this pop-up sub menu... if you know it's there... but it is now the only way of doing so.
Furthermore, if you have anything that is a free action - such as the prepare weapon skill - you CANNOT access this ability now AT ALL, because it is not tied to any of your resource buttons... and you cannot undo this once it is done.
Please just take a minute to let the sheer high school level of bad design percolate for a minute.