I keep getting a black screen when I sleep in camp.
I am getting the same issue. I also black screened after resting in the starting mission upon re-entering the cave (was trying to farm bats for some early candies).
It's happening to me as well.
I am not sure if this is the only solution at the moment, but what (sometimes) works for me is saving, then loading the save again. The game sometimes let's you open the menu (X key) when you're at that black screen. At that point, just open it and save.
Other than that, take safety measures against it, and save every time before you set camp. Hope a patch comes out for that soon.
EDIT: Something else that also works: get in or out of something. Anything. A city, Faun's tavern, a dungeon, anything works. You don't see it, but your character is still moving.
So if, for example, you set camp just below Faun's tavern. If you get a black screen after waking up, simply hold up and your character will move, entering the tavern. At that point, the game will probably start showing stuff again. After that, just get out of the place again.
Hi! I've actually gone over this topic before, but I'll gladly post about it again.
What's going on here with the Black Screen is actually just a really long load time- a side effect of the sheer scope/size of the game.
To really give an example of what I'm talking about, let's go over the Campsite map.
Of the several maps in the game, this one has been around for a particularly long time in the game's development process, and more and more script keeps getting added to it throughout the many updates.
As an example, when Wendigo Princess was added to the game, they added events that check whether she's in your party or not, as well as some adult animations.
Doesn't sound like much, right? But, this is the case with pretty much every unique recruitable character you can add to your team, which does add up- And this is only a fraction of what's in the campsite.
When you sleep at camp, this causes you to leave the map.
About 5 seconds or so pass, and the new map's data has loaded, ergo, your menu is available.
So why is the screen still black after that? Well, I'm pretty sure this is because of the previous map's scripts still being in the process of unloading, which needs to be finished before the graphics of the new map can be loaded... or something.
As Hiyuman's post implies, you have full access to the world map after a short few seconds, at which point you can enter another map instead of waiting for the full load time, save and load the game, or even blindly walk to your next destination provided you have a good memory of the map.
I'm not entirely sure how long it takes for the new map to load without doing any of the above now- at the time of the Bloomfest update though, it was something like 15 seconds.
Hope this helps! Wish they'd split up their eventing more, it's kinda just inconvenient.
(As a sidenote, it could also be some other issue such as an optimization plugin, but I'm not entirely sure.)
Edit: It's also worth noting that other map transitions will have noticeably less/more load time, it just so happens that the campsite has the longest.