Testing version: 10784
What were you doing: Trying to change app theme
What feature did you use: Themes tab in settings
What happened: Nothing; can’t change theme, I’m now stuck with Charcoal
What did you expect to happen: Theme should change when I click it in theme settings
Oh no! I encountered the same issue… and I’m stuck with a theme that I usually am not comfortable with. I was just trying 
I discovered the same issue on my Mac this morning too, but I’m pretty sure there will be a fix for this early next week.
In the meantime we could either live with the stuck theme for a few days, or fix it by this workaround:
It should be safe to install the previous build over current, but probably wise to run a full backup first.
Good point thanks for the tip. I’ll probably wait for the next update.
I’m on 10784 and have no problem changing themes.
On macOS? The bug doesn’t affect iOS.
Okay it started working now apparently on macOS too 
I also encountered this bug and I discovered something interesting here.
Basically I can change theme if I switch my mac’s dark/light mode after starting Bear.
If I don’t do that I am not able to change theme.
I’m on 10784 as well.
This seems pretty consistent:
Oh right, I actually changed to light theme and back before trying to change Bear theme again, so maybe that’s what I was seeing.
Nice to see you back 
So to reiterate:
Steps to reproduce: